Bump Rugged to 0.27.0
Release notes: https://github.com/libgit2/libgit2/releases/tag/v0.27.0
This version solves a significant performance issue with generating large diffs: https://github.com/libgit2/libgit2/issues/4460
Release notes: https://github.com/libgit2/libgit2/releases/tag/v0.27.0
This version solves a significant performance issue with generating large diffs: https://github.com/libgit2/libgit2/issues/4460