Merge tag 'v1.9.1'

Dropped 942ba14 as sortedcache switched to hashset_str in 8dc52d0.

Merge pull request libgit2#7084 from libgit2/ethomson/v1.9.1

Merge pull request libgit2#6990 from libgit2/ethomson/ci

Merge pull request libgit2#6936 from libgit2/ethomson/v1.8.4

libgit2 v1.8.4

Merge pull request libgit2#6931 from libgit2/ethomson/v1.8.3

Merge tag 'v1.8.1'

Merge pull request libgit2#6830 from libgit2/ethomson/v1.8.2

libgit2 v1.8.2

Merge pull request libgit2#6830 from libgit2/ethomson/v1.8.2

libgit2 v1.8.2

Remove tests, fuzzers and github

Merge pull request libgit2#6817 from libgit2/ethomson/v1.8.1

libgit2 v1.8.1