devel/rubygem-gitlab-experiment: update to 0.7.1

Required for gitlab-ce 14.10.
Changelog:
https://gitlab.com/gitlab-org/ruby/gems/gitlab-experiment/-/tags/v0.7.1

Fixes some concurrency issues with rollout strategies
Fixes issue with [before/around/after]_run callbacks

MFH: 2022Q2
(cherry picked from commit 1d36c8d06effacab2b60a351e6841acc990f08ca)