Bump rsa from 4.6 to 4.7 in /api (Flagsmith#93)

Bumps [rsa](https://github.com/sybrenstuvel/python-rsa) from 4.6 to 4.7.
- [Release notes](https://github.com/sybrenstuvel/python-rsa/releases)
- [Changelog](https://github.com/sybrenstuvel/python-rsa/blob/main/CHANGELOG.md)
- [Commits](sybrenstuvel/python-rsa@version-4.6...version-4.7)

---
updated-dependencies:
- dependency-name: rsa
  dependency-type: indirect
...

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api/requirements.txt

@@ -199,7 +199,7 @@ requests==2.24.0
     #   smsapi-client
     #   twilio
     #   yubico-client
-rsa==4.6
+rsa==4.7
     # via
     #   google-auth
     #   oauth2client