feat: combine multiple commit-lists to one if heading is undefined

[itayo]

This will combine multiple commit-lists to 1 list without a new heading when the heading variable is undefined

[itayo]

A better solution would be to make the commit-list take multiple areas and combine them.
as we use squash and merges some goes ass merges and some goes as commits.

[itayo]

But that i have no idea how to fix

[cookpete]

Nice work. Sorry for the delay… 😬