Add redis SSL support

[dswillr]

What do these changes do?

Add redis SSL support

Are there changes in behavior for the user?

RedisCache should now have a configuration option for ssl

Related issue number

No issues opened around this

Checklist

• [ ] I think the code is well written
• [ ] Unit tests for the changes exist
• [ ] Documentation reflects the changes
• [ ] Add a new news fragment into the CHANGES folder
  • name it <issue_id>.<type> (e.g. 588.bugfix)
  • if you don't have an issue_id change it to the pr id after creating the PR
  • ensure type is one of the following:
    • .feature: Signifying a new feature.
    • .bugfix: Signifying a bug fix.
    • .doc: Signifying a documentation improvement.
    • .removal: Signifying a deprecation or removal of public API.
    • .misc: A ticket has been closed, but it is not of interest to users.
  • Make sure to use full sentences with correct case and punctuation, for example: Fix issue with non-ascii contents in doctest text files.

[eigenein]

Bump! Is there any progress on getting it merged yet?

[smelnyk]

Bump! as well

[Dreamsorcerer]

Sorry for the delay. We've since migrated over to redis, so this PR will need updating. It's probably easier to create a new one, so I'll close this one. If someone can verify this still relates to the new redis library and create a new PR, that would be great.