Update of Gitaly gem

What does this MR do?

As the new version of Gitaly server is used after !33302 (merged) got merged we can update current version of gem to get support of the new features and fields exposed by the new version of the contract.
New version of gem is already available at https://rubygems.org/gems/gitaly/versions/13.1.0.pre.rc1

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content