SIENTIAPDE-1646

Update dependencies and refactor MLFlow activities

- Replaced direct GitHub dependencies in `requirements.txt` with specific versioned packages for `sientia_do` and `sientia_model`.
- Refactored imports in `activities.py` to streamline the code structure.
- Enhanced the `MLFlow` class in `mlflow.py` by introducing a method to resolve model aliases, improving flexibility in model lookups.
- Simplified shutdown logic in `worker.py` for better readability.
- Added new tests for MLFlow activities and improved existing test coverage for data handling and model retraining processes.

requirements.txt

@@ -3,8 +3,8 @@ psycopg2-binary
 sqlalchemy
 asyncua
 redis
-git+ssh://git@github.com/Aignosi/sientia-dataops-library.git@1.12.0
-git+ssh://git@github.com/Aignosi/sientia-model-library.git@0.8.1
+sientia_do==1.12.0
+sientia_model==0.8.2
 prometheus-client
 botocore
 boto3