Changelog not found if title case is used in CHANGELOG.md

[JB26]

How are you running Renovate?

None

Which platform you running Renovate on?

github.com

Which version of Renovate are you using?

43.129.0

Please tell us more about your question or problem

The "Release Notes" section in an update pull request for oauth2-proxy/oauth2-proxy package is empty.

They are using title case in headings of the CHANGELOG.md. This prevents the parser from finding the right heading. Instead it than takes the second level heading from the pre-release section, which results in empty "Release Notes".

Reproduction Repo

https://github.com/JB26/renovatebot-oauth2-proxy-changelog

Possible fix

I suggest to make the heading lower case before comparing it. I think it is a fair assumption that a project might use title case in the headings.

JB26@43b58aa

Other fixes, I can think of, might be to compare the changes loaded from github release with the CHANGELOG.md changes and choose the "better" one (maybe the one with the larger body?).

Maybe it would also make sense to try to detect the prerelease heading and skip it?

But I think in this case the lowers case comparison is enough.

Thanks for looking into this :)

Logs (if relevant)

No response