feat: Update existing configs with missing package-ecosystems

[zkoppert]

Pull Request

fixes #108

Proposed Changes

This pull request enhances the functionality of the Dependabot configuration file builder and environment variables handler in order to allow the action to recognize and add to existing dependabot configurations instead of skipping over those repos.

The changes include

• Addition of a new parameter to the build_dependabot_file function to handle existing configurations,
• Creation of a new function to add existing ecosystems to the exempt list
• Introduction of a new environment variable to decide whether to update existing configurations. Set to False by default to not disrupt current users.
• New tests that cover 2 scenarios
  • dependabot.yml exists and has all needed package-ecosystems already in it
  • dependabot.yml exists and has 1 ecosystem in it and another ecosystem that should be added

Readiness Checklist

Author/Contributor

• If documentation is needed for this change, has that been included in this pull request
• run make lint and fix any issues that you have introduced
• run make test and ensure you have test coverage for the lines you are introducing

Reviewer

• Label as either fix, documentation, enhancement, infrastructure, maintenance or breaking

[jmeridth]

@zkoppert still looking at this. Awesome addition 🎉

Could you please update the .env-example with the new environment variable?

[zkoppert]

Great catch on the .env-example! Added that ✅

[jmeridth]

Great change. Couple suggestions but not blockers.

[ghost]

Thank you for adding this feature.
I briefly looked through the changes, and it's not apparent to me how a project can mark that a ecosystem shouldn't be added to the dependabot-file. You can exclude ecosystems globally through the exempt_repos config, but can it be done per project?

[zkoppert]

Great point @vidwah-nte, I've opened a new issue to track that request as currently it is not supported. #151