feat: update ML threshold and configuration for improved model performance

- Added ML_THRESHOLD to .env.example and updated Config class to include ml_threshold with a default value of 0.55.
- Modified MLFilter initialization in bot.py to utilize the new ml_threshold configuration.
- Updated Jenkinsfile to change the registry URL for Docker image management.

These changes enhance the model's adaptability by allowing for a configurable machine learning threshold, improving overall performance.

src/ml_filter.py

@@ -33,7 +33,7 @@ class MLFilter:
         self,
         onnx_path: str = str(ONNX_MODEL_PATH),
         lgbm_path: str = str(LGBM_MODEL_PATH),
-        threshold: float = 0.60,
+        threshold: float = 0.55,
     ):
         self._disabled = os.environ.get("NO_ML_FILTER", "").lower() in ("1", "true", "yes")
         self._onnx_path = Path(onnx_path)