v1.0.1

Pin new versions of required actions to fix potential problems with GitHub authentication & remove non-essential files from the release build that aren't required for the action to run.

Updated README to include information about forwarding $GITHUB_TOKEN:

name: ...
on: [ push ]
jobs:
  test-code:
    name: Run Plugin Tests
    runs-on: ubuntu-20.04 # pmmp-php-build doesn't work on ubuntu-latest yet
    steps:
      - name: ...
        uses: actions/checkout@v3
      - name: ...
        uses: nxtlvlsoftware/run-phpstan-pmmp-action@v1
        env:
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }} // NEW