adds githubWorkflowBuildSbtStepPreamble, removes setting crossScalaVersions

sbt-build.diff

diff --git a/build.sbt b/build.sbt
index ed64964..95294a6 100644
--- a/build.sbt
+++ b/build.sbt
@@ -16,8 +16,8 @@ def dev(ghUser: String, name: String, email: String): Developer =
 
 inThisBuild(
   List(
+    githubWorkflowBuildSbtStepPreamble := Seq(),
     scalaVersion := Scala3,
-    crossScalaVersions := List(Scala212, Scala213, Scala3),
     tlBaseVersion := "2.5",
     startYear := Some(2018),
     licenses := Seq(("MIT", url("https://github.com/typelevel/fs2-grpc/blob/master/LICENSE"))),
@@ -64,7 +64,7 @@ lazy val codegen = (projectMatrix in file("codegen"))
       "2.12" -> "2.5.3",
       "2.13" -> "2.5.3",
       "3" -> "2.5.3"
-    )
+    ),
   )
   .jvmPlatform(scalaVersions = Seq(Scala212, Scala213, Scala3))
 
@@ -76,7 +76,6 @@ lazy val plugin = project
   .settings(
     name := "sbt-fs2-grpc",
     scalaVersion := Scala212,
-    crossScalaVersions := List(Scala212),
     tlVersionIntroduced := Map("2.12" -> "2.5.3"),
     sbtPlugin := true,
     buildInfoPackage := "fs2.grpc.buildinfo",
@@ -99,10 +98,17 @@ lazy val runtime = (projectMatrix in file("runtime"))
   .defaultAxes(axesDefault: _*)
   .settings(
     name := "fs2-grpc-runtime",
-    crossScalaVersions := List(Scala212, Scala213, Scala3),
     tlVersionIntroduced := Map("2.12" -> "2.5.3", "2.13" -> "2.5.3", "3" -> "2.5.3"),
     libraryDependencies ++= List(fs2, catsEffect, grpcApi) ++ List(grpcNetty, ceTestkit, ceMunit).map(_ % Test),
-    Test / parallelExecution := false
+    Test / parallelExecution := false,
+    scalacOptions ++= {
+      // https://discord.com/channels/632277896739946517/1070110102650097706/1070110232988090368
+      // emulating https://github.com/typelevel/sbt-typelevel/blob/8b7e77e91bd34038605eb71e8d78fb8a558321d6/settings/src/main/scala/org/typelevel/sbt/TypelevelSettingsPlugin.scala#L155
+      CrossVersion.partialVersion(scalaVersion.value) match {
+        case Some((3, _)) => Seq("-language:implicitConversions", "-Ykind-projector", "-source:3.0-migration")
+        case _ => Seq.empty
+      }
+    }
   )
   .jvmPlatform(scalaVersions = Seq(Scala212, Scala213, Scala3))
 
@@ -124,7 +130,6 @@ lazy val e2e = (projectMatrix in file("e2e"))
   .defaultAxes(axesDefault: _*)
   .enablePlugins(LocalCodeGenPlugin, BuildInfoPlugin, NoPublishPlugin)
   .settings(
-    crossScalaVersions := Seq(Scala212, Scala213, Scala3),
     codeGenClasspath := (codeGenJVM212 / Compile / fullClasspath).value,
     libraryDependencies := Nil,
     libraryDependencies ++= List(scalaPbGrpcRuntime, scalaPbRuntime, scalaPbRuntime % "protobuf", ceMunit % Test),
@@ -134,6 +139,14 @@ lazy val e2e = (projectMatrix in file("e2e"))
     ),
     buildInfoPackage := "fs2.grpc.e2e.buildinfo",
     buildInfoKeys := Seq[BuildInfoKey]("sourceManaged" -> (Compile / sourceManaged).value / "fs2-grpc"),
-    githubWorkflowArtifactUpload := false
+    githubWorkflowArtifactUpload := false,
+    scalacOptions ++= {
+      // https://discord.com/channels/632277896739946517/1070110102650097706/1070110232988090368
+      // emulating https://github.com/typelevel/sbt-typelevel/blob/8b7e77e91bd34038605eb71e8d78fb8a558321d6/settings/src/main/scala/org/typelevel/sbt/TypelevelSettingsPlugin.scala#L155
+      CrossVersion.partialVersion(scalaVersion.value) match {
+        case Some((3, _)) => Seq("-language:implicitConversions", "-Ykind-projector", "-source:3.0-migration")
+        case _ => Seq.empty
+      }
+    }
   )
   .jvmPlatform(scalaVersions = Seq(Scala212, Scala213, Scala3))

sbt-githubWorkflowGenerate.diff

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 0e821de..d3ca4b9 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -28,13 +28,8 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest]
-        scala: [2.12.17, 2.13.10, 3.2.2]
+        scala: [3.2.2]
         java: [temurin@8, temurin@17]
-        exclude:
-          - scala: 2.12.17
-            java: temurin@17
-          - scala: 2.13.10
-            java: temurin@17
     runs-on: ${{ matrix.os }}
     steps:
       - name: Checkout current branch (full)
@@ -91,18 +86,18 @@ jobs:
 
       - name: Check headers and formatting
         if: matrix.java == 'temurin@8' && matrix.os == 'ubuntu-latest'
-        run: sbt '++ ${{ matrix.scala }}' headerCheckAll scalafmtCheckAll 'project /' scalafmtSbtCheck
+        run: sbt headerCheckAll scalafmtCheckAll 'project /' scalafmtSbtCheck
 
       - name: Test
-        run: sbt '++ ${{ matrix.scala }}' test
+        run: sbt test
 
       - name: Check binary compatibility
         if: matrix.java == 'temurin@8' && matrix.os == 'ubuntu-latest'
-        run: sbt '++ ${{ matrix.scala }}' mimaReportBinaryIssues
+        run: sbt mimaReportBinaryIssues
 
       - name: Generate API documentation
         if: matrix.java == 'temurin@8' && matrix.os == 'ubuntu-latest'
-        run: sbt '++ ${{ matrix.scala }}' doc
+        run: sbt doc
 
       - name: Make target directories
         if: github.event_name != 'pull_request' && (startsWith(github.ref, 'refs/tags/v') || github.ref == 'refs/heads/main')
@@ -179,26 +174,6 @@ jobs:
             ~/Library/Caches/Coursier/v1
           key: ${{ runner.os }}-sbt-cache-v2-${{ hashFiles('**/*.sbt') }}-${{ hashFiles('project/build.properties') }}
 
-      - name: Download target directories (2.12.17)
-        uses: actions/download-artifact@v3
-        with:
-          name: target-${{ matrix.os }}-${{ matrix.java }}-2.12.17
-
-      - name: Inflate target directories (2.12.17)
-        run: |
-          tar xf targets.tar
-          rm targets.tar
-
-      - name: Download target directories (2.13.10)
-        uses: actions/download-artifact@v3
-        with:
-          name: target-${{ matrix.os }}-${{ matrix.java }}-2.13.10
-
-      - name: Inflate target directories (2.13.10)
-        run: |
-          tar xf targets.tar
-          rm targets.tar
-
       - name: Download target directories (3.2.2)
         uses: actions/download-artifact@v3
         with: