charlock_holmes v0.7.7 resolves a C++ build issue
(https://github.com/brianmario/charlock_holmes/compare/0.7.6..v0.7.7) on
some machines.

This may also resolve a CentOS 6 build issue
(https://gitlab.com/gitlab-org/omnibus-gitlab/-/issues/5682) since the
gem will be available for gitaly-ruby using the newer compiler.