Support regex repo pattern

[jpoehnelt]

We have many repositories in our org. It would be nice to match on some prefix or other pattern.

repos: |
  org/foo-.*$
  org/foobar

Constraint would require always having a defined org.

[BetaHuhn]

Related to #83 (Branch Name Wildcard Support). I think it makes sense to support regex in both branches and the repository name.

This is definitely something I want to add, I just don't have the time at the moment to work on this myself.

If you or anyone else wants to create a PR, happy to review and merge it.