Add MaxMind secrets

[minhaminha]

Jira Ticket

Environments Affected

Won't affect any environment until I update the secrets for each other them (separate API keys for each env, starting with Staging for testing)

Announce New Release

• After merging, I will follow these instructions
  to announce a new commcare-cloud release.

[minhaminha]

Since I eventually will use commands to edit the secrets, I think that means this warrants a changelog PR based on the link in the description... will follow up shortly

[esoergel]

I don't think you need to announce this in the changelog, as there's no action required by third parties