Description

This PR add 2 new settings to handle tag formats;

• legacy_tag_formats allowing tag format to change over time while retaining the ability to work with legacy version
• ignored_tag_formats to specify expected tag that should not raise InvalidVersion.

So projects which change tag formats and have expected but non-version tags can have these settings:

tag_format = "v${version}"
legacy_tag_formats = [
	"${version}",
	"project-prefix-${version}",
]
ignored_tag_formats = [
	"stable",
	"other-project-*",
]

By doing so, I had to start grouping tag handling and introduce a tags.TagRules object which is responsible for handling all tags rules, initially spread over tag_format, version_schemes and version_providers

Checklist

• Add test cases to all the changes you introduce
• Run ./scripts/format and ./scripts/test locally to ensure this change passes linter check and test
• Test the changes on the local machine manually
• Update the documentation for the changes

Expected behavior

• I can change tag format and still being able to:
  • bump versions (aka. find the increment and commits range)
  • generate changelog (full, incremental, version range)
• I can generate a changelog without warnings for expected tags

Steps to Test This Pull Request

• create a project
• set version_provider = "scm" (not mandatory but allows testing the full scope)
• bump some versions with an initial tag_format
• move current tag_format in legacy_tag_format and define a new tag_format
• bump a version with changelog:
  • current version should be properly identified
  • increment should properly been found
  • new version should be correct
  • generated changelog generation should be correct (both new and old version formats)
  • new tag should respect the new tag_format

then:

• add random-* to ignored_tag_formats
• tag any commit with random-tag
• run cz changelog
  • there shouldn't be any warning

Additional context

There might be a 2nd PR handling a changelog_version_format setting to customize the version rendering in the changelog so:

• it's not the tag format anymore (problematic with some prefixes, like for monorepos)
• have a uniform version display across tag_format changes