Feature/git tag semver

Please have a look at this PR to add support for git url with valid semver tags.

This is what we discussed in issue #3 :)
What about `git+ssh://git@git.example.com:b/b.git#various-changes`? This will be detected as a semver pattern which it's not.

It might be less risky to skip the check if the `versionString` is not detected as a valid semver pattern (potentially prefixed with `v`). Unless you have a better idea. :)

Tests for that would be useful as well.