django-minio-backend 3.5.0

Fixes bug introduced in issue/#34

Due to a bug all public bucket urls were generated using the internal client. Due to this fault public urls did not respect the value of MINIO_EXTERNAL_ENDPOINT.
The old fake client was repurposed as an external client.

Additional changes:

• Dropped the v prefix from version numbers
• GH workflows updated to the latest Ubuntu and Python versions and updated the watched tags
• README.md updated with new Python version recommendations