Improve changelog management

[Ndpnt]

• Improve changelog validation:
  • Ensure that it can be parsed
  • Ensure that funder credit is present
  • Ensure that changes are present and well formed in the Unreleased section
• Remove confusing Unreleased section title after releasing a version
• Auto add link to related pull request of a released version
• Allow to skip changelog validation by adding following section in the changelog:

## Unreleased [no-release]

 _Modifications made in this changeset do not alter its behavior or functionality from the perspective of the end user or other interacting systems. It does not add new features, does not enhance existing features, or alters the behavior of the software in a way that affects its use._

Remove dependency to external GitHub Action superfaceai/release-changelog-action

Fixes #1009

[MattiSG]

As discussed synchronously with @Ndpnt and @clementbiron, the current implementation has the following limitations:

1. Contributors will receive a test failure until a maintainer adds the No Release label.
2. Maintainers will need to manually trigger a test run after adding the No Release label.
3. Increased vendor lock-in with GitHub.

An alternative could be to offer a line to copy-paste in the Unreleased section, in which the contributor certifies that, to the best of their knowledge, the contribution has no functional impact and should not trigger a release. Such an implementation would have the following limitations:

1. Provide a green check mark for the check changelog check when the line is present, leaving more room for an accidental lack of release from a tired maintainer.
2. Add a commit erasing the “Unreleased” section after each non-functional branch merge.
3. Force an unusual action from contributors: copy-pasting a specific line from the CONTRIBUTING file.

[MattiSG]

(partial review)

[MattiSG]

Almost there, but the checks and the option syntax should be corrected.

[MattiSG]

• Follow the spec.
• Ensure there is a closing full stop.
• Why allow multiline?

Suggested change

	static FUNDER_REGEX = /^> Development of this release was(.+)$/m;
	static FUNDER_REGEX = /^> Development of this release was supported by (.+)\.$/;

[Ndpnt]

• Multiline is required to have ^ and $ to match the begin/end of each line (not only begin/end of string). This is essential as we analyze the entire release content to verify the funder.
• We have an issue with the specification regarding certain release funders formatted as follows: > Development of this release was made on a volunteer basis by …. Should we modify these types of funder sentences, or should we adjust the specification accordingly?

[MattiSG]

We should adjust the spec as volunteer contributions are an integral part of the contribution workflow.

Gotcha for the multiline, I had misunderstood this flag as valid for the match, not for the input.

[MattiSG]

👏 🚀

[MattiSG]

Suggested change

	static FUNDER_REGEX = /^> Development of this release (?:was supported by|was made on a volunteer basis by)(.+)\.$/m;
	static FUNDER_REGEX = /^> Development of this release was (?:supported by|made on a volunteer basis by)(.+)\.$/m;