Teach Bedevere to suggest regenerated `configure` file

[arhadthedev]

To modify configure.ac, contributors need to use the https://github.com/tiran/cpython_autoconf Docker image. However, Windows users are out of luck; for my contributions I need to use a throwaway GitHub Actions workflow.

Probably, we should teach Bedevere to call this image for us, save the generated configure as a workflow artifact and post a link with an explanatory note on what it's for and how to use it.

I propose to implement it as a GitHub action (with a Python link poster) because it already supports custom Docker images. Also, it would be the first step towards gh-344.

[arhadthedev]

Triggering Bedevere via events will create something like this:

but worse. The whole approach needs to be redesigned.

[corona10]

To modify configure.ac, contributors need to use the https://github.com/tiran/cpython_autoconf Docker image. However, Windows users are out of luck; for my contributions I need to use a throwaway GitHub Actions workflow.

I am not sure for this suggestion.
If user didn't regenerate configure file, how do we can belive that user verify the change in their local environment?

[arhadthedev]

Fortunately, Check if generated files are up to date already prints a diff that perfectly solves the underlying issue without adding anything to Bedevere:

          if test -n "$changes"; then
            echo "Generated files not up to date."
            echo "Perhaps you forgot to run make regen-all or build.bat --regen. ;)"
            echo "configure files must be regenerated with a specific version of autoconf."
            echo "$changes"
            echo ""
            git diff --staged || true
            exit 1
          fi

Thus closing.