Update project structure and enhance model persistence

- Added new model and scaler files to .gitignore and output directory.
- Updated Dockerfile to create output/models directory.
- Revised README to include instructions for using a .env file for configuration.
- Enhanced config.py to load database credentials from environment variables.
- Implemented model saving functionality in salary_predictor.py for consistent and inconsistent earners.

requirements.txt

@@ -1,13 +1,15 @@
-sqlalchemy
-pandas
-numpy
-matplotlib
-seaborn
-matplotlib-venn
-wordcloud
-scikit-learn
-psycopg2-binary
+sqlalchemy>=2.0.0
+pandas>=1.5.0
+numpy>=1.21.0
+matplotlib>=3.5.0
+seaborn>=0.12.0
+matplotlib-venn>=0.11.7
+wordcloud>=1.8.0
+scikit-learn>=1.0.0
+psycopg2-binary>=2.9.0
 fastapi>=0.68.0
 uvicorn>=0.15.0
 pydantic>=1.8.0
-python-multipart>=0.0.5 
+python-multipart>=0.0.5 
+python-dotenv>=0.19.0
+joblib>=1.1.0