ruby: Upgrade to Rugged 1.0.1

With v1.0, libgit2 released its first stable major version since forever and as Rugged follows the same versioning scheme, it also released v1.0 of the Gem. This caused us to be blocked on upgrading libgit2/Rugged as some of our dependencies were depending on ~>0.28.

The two last dependencies which did depend on that are licensee and gitlab-gollum-lib. While the latter has a new Gem pushed which now depends on ~>1.0 of rugged, licensee didn't yet release a new version but has the fix on its master branch.

This commit here thus upgrades both Gems, which allows us to finally make use of rugged v1.0 and later.

Relates to #2856 (closed). Replaces !2641 (closed)