Use GitLab Pages v0.9.1

What does this MR do?

Updates GitLab Pages to v0.9.1

Are there points in the code the reviewer needs to double check?

Why was this MR needed?

Fixes a number of regressions in Pages; allows Omnibus support to not have to worry about which version of Pages is actually being deployed.

Screenshots (if relevant)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• API support added
• Tests added for this feature/bug
• Review
  • Has been reviewed by Backend
• Conform by the merge request performance guides
• Conform by the style guides
• Squashed related commits together
• Internationalization required/considered
• End-to-end tests pass (package-and-qa manual pipeline job)

What are the relevant issue numbers?

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/45639

Related to gitlab-pages#130 (closed)