Update capybara gem to v3.39.0

What does this MR do?

This matches the update in GitLab Rails: gitlab-org/gitlab!117172 (merged)

Ruby 3.1 extracted the matrix gem into a separate gem, and as a result Capybara needs to have the gem explicitly required. This pulls in https://github.com/teamcapybara/capybara/pull/2468.

Related issues

Ruby 3.1 epic: gitlab-org&10034 (closed)

Checklist

See Definition of done.

For anything in this list which will not be completed, please provide a reason in the MR discussion.

Required

• Merge Request Title and Description are up to date, accurate, and descriptive
• MR targeting the appropriate branch
• MR has a green pipeline on GitLab.com
• When ready for review, MR is labeled "~workflow::ready for review" per the Distribution MR workflow

Expected (please provide an explanation if not completing)

• Test plan indicating conditions for success has been posted and passes
• Documentation created/updated
• Tests added
• Integration tests added to GitLab QA
• Equivalent MR/issue for omnibus-gitlab opened
• Validate potential values for new configuration settings. Formats such as integer 10, duration 10s, URI scheme://user:passwd@host:port may require quotation or other special handling when rendered in a template and written to a configuration file.