Update ruby-saml to 1.7.2 and omniauth-saml to 1.10.0 (CVE-2017-11428, CVE-2017-11430)

What does this MR do?

Updates omniauth-saml to 1.10.0 (to address CVE-2017-11430) and ruby-saml to 1.7.2 (to address CVE-2017-11428)

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

• omniauth-saml changelog: https://gitlab.com/gitlab-org/gitlab-ce/issues/43806#note_63095285
• ruby-saml changelog: https://gitlab.com/gitlab-org/gitlab-ce/issues/43806#note_63095836

Why was this MR needed?

To address two security vulnerabilities: CVE-2017-11428 and CVE-2017-11430.

Does this MR meet the acceptance criteria?

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

What are the relevant issue numbers?

Closes #43806