You can use while in workflow `steps.run`

while-in-workflow.yaml

name: using while in Github Workflow

on:
  push:
    branches:
      - '**'

jobs:
  test-loop:
    timeout-minutes: 2
    runs-on: ubuntu-latest
    permissions:
      contents: write
    steps:
      - uses: actions/checkout@v2
        with:
          fetch-depth: 1
          token: ${{ secrets.GITHUB_TOKEN }}
      - name: 'while'
        run: |
          while : ; do
            git pull --rebase || break
            git push && break
          done