* omniauth-google-oauth2: Google will be deprecating its support for the
Google+ API, which currently omniauth-google-oauth2 uses to retrieve
user info. The bump in omniauth-google-oauth2 requires an upgrade to
ruby-jwt v2+ to support the verification of multiple issue providers
(https://github.com/zquestz/omniauth-google-oauth2/pull/345).

* jwt: This has the most number of changes that need to be
reviewed: https://github.com/jwt/ruby-jwt/blob/master/CHANGELOG.md

* oauth2: Needed to support ruby-jwt v2+:
https://github.com/oauth-xx/oauth2/blob/master/CHANGELOG.md

* omniauth-azure-oauth2 needs a version bump to support ruby-jwt v2+.

* omniauth: This version bump only involves backstage improvements:
https://github.com/omniauth/omniauth/releases

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/55668