Fix deployment error with pydantic_settings

- Add pydantic-settings to requirements.txt
- Update config.py to handle missing pydantic_settings module
- Use fallback to regular pydantic BaseSettings if pydantic_settings is not available

app/core/config.py

@@ -1,6 +1,10 @@
 from pathlib import Path
 
-from pydantic_settings import BaseSettings
+# Try to import from pydantic_settings, fall back to pydantic if not available
+try:
+    from pydantic_settings import BaseSettings
+except ImportError:
+    from pydantic import BaseSettings
 
 
 class Settings(BaseSettings):

requirements.txt

@@ -3,5 +3,6 @@ uvicorn>=0.15.0
 sqlalchemy>=1.4.0
 alembic>=1.7.0
 pydantic>=2.0.0
+pydantic-settings>=2.0.0
 python-dotenv>=0.19.0
 ruff>=0.0.270