GitHub Actions steps to cache VS Code stable when running extension tests

steps.yml

      - name: Get VS Code versions
        run: curl --output vscode-stable-versions.json https://update.code.visualstudio.com/api/releases/stable
      - uses: actions/cache@v1
        with:
          path: .vscode-test/
          key: ${{ runner.os }}-vscode-test-${{ hashFiles('vscode-stable-versions.json') }}
          restore-keys: |
            ${{ runner.os }}-vscode-test-