Update GitHub Actions to replace `::set-output`

[PortableProgrammer]

Per the 11 October 2022 GitHub Blog, ::set-output is deprecated and should be replaced.

In docker-image.yml, switch to $GITHUB_ENV:

# Example actions
-
  name: Prepare
  id: prepare
  run: |
    echo "docker_image=${DOCKER_IMAGE}" >> "$GITHUB_ENV"
    echo "version=${VERSION}" >> "$GITHUB_ENV"

- 
  name: Docker Check Manifest
  run: |
    docker run --rm mplatform/mquery ${{ env.docker_image }}:${{ env.version }}