3.0 Release

[michaelboulton]

• MQTT as an optional extra instead of being in core (pip install tavern[mqtt])
• More recent version of pytest
• Convert all type annotations to py3.11+ versions and make that the minimum version supported
• Better grpc support / stabilisation of features
  • It might be useful to allow a flag when mkaing a grpc request that serialises the message into a protobuf.Any message . This is sometimes useful
• Clean up docs to indicate gRPC support on the front page, classifiers, etc?
• Remove _deprecated_recurse_access_key
• Update to protobuf 5?

[michaelboulton]

Probably also want to expose some internals (like Pytest) so that plugins dont have to import from private tavern modules