Update gitlab-glfm-markdown and prometheus-client-mmap gems

Both Rust gems need to be updated together because they
depend on rb-sys ~> 0.9.109.

The prometheus-client-mmap update fixes a seg fault happening in
staging:
https://gitlab.com/gitlab-org/ruby/gems/prometheus-client-mmap/-/merge_requests/196
(https://gitlab.com/gitlab-org/ruby/gems/prometheus-client-mmap/-/issues/69).

Changelog: changed