"Only Redis glob strings are supported: " on unpublish when using redis as cache store

[sstrudeau]

Pretty sure this is the issue: https://github.com/contentful/contentful_rails/blob/1ebf57c7bab06f3c0349bfdda911f041f9147d6d/lib/contentful_rails/engine.rb#L56

Redis doesn't support regex and instead supports "glob" strings for matching expiration (and according to the Rails docs for expire_fragment, neither does memcache): https://apidock.com/rails/v6.1.3.1/AbstractController/Caching/Fragments/expire_fragment

I'm not sure the best method to fix this; if there is just one key and it is deterministic, passing a string instead of a regex would be better supported.