fix(python): standardize Python headers in the changelog

[dandhlee]

Ported over existing entry from the Ruby-yoshi changelog updater. Only modifying for header changes and removing links in the version titles.

For any headers of size 2 or 3 for version change entries, they will be standardized to header size 2.

For any headers of size 2 or 3 for change type entries, they will be standardized to header size 3.

Fixes #1389 🦕

[dazuma]

One caveat: This will affect EVERYONE who uses the python strategy, including non-Google users. Please make sure that is what you want. (For the Yoshi Ruby team, for example, we have a separate ruby-yoshi strategy subclass specific to our desired use case, and we modified that subclass rather than the main ruby strategy.)

[dandhlee]

Thank you for taking a look! I think the inconsistent header problem would definitely benefit all users including non-Googlers.

As per dropping the version header link as well, that might be less desired for some folks but with the reasons I stated in the comments I think it is alright to drop the links to those. The information is still available on the GitHub page itself if folks were interested. But, if others feel strongly against this I'll be happy to drop it and only include the inconsistent header changes for all of Python.

[dazuma]

I definitely defer to @bcoe on changes that could affect a large number of users.

[dandhlee]

Please take a look again!

[chingor13]

FWIW, the default changelog contents is being generated by conventional-changelog-writer. It's unclear from their docs and examples whether this is a feature or a bug.

cc @bcoe

edit: maybe this is a bug: conventional-changelog/conventional-changelog#867

[bcoe]

I think this is a feature which predates my work on the project, the idea being that features jump out more in the CHANGELOG than bug fixes.

[bcoe]

I would rather this change happen upstream in conventional-changelog-writer, than carry custom regex to rewrite the header size.

Care to make a PR there instead?

[bcoe]

I've been talking to @dandhlee, we're working on an upstream fix.