(Usability) Prefixed releases with release-please are not processed with semver

[chrisvander]

Hi,

I use a repository setup that involves releasing both a Helm chart and the app simultaneously. How release-please handles this is with a prefix. So I have tags of the style appname-v1.0.0-... and appname-helm-v1.0.0-.... I've changed the "match" to match appname-v[0-9]* but of course it does not filter the prefix before semver.parse(), which fails.

Could I have a way to either specify a group in the match to use (like appname-(v[0-9]*.*)) or some other method to match/filter a prefix?

A more general purpose solution could simply be an arbitrary format function that takes the tag and does something to it to make it semver compatible. I could do this on the other side, but I like the work you've put in to making the commit hash and number of commits to a semver-compatible format.