Fix code review issues: update datetime.utcnow() to datetime.now(timezone.utc) and fix Docker configs

Co-authored-by: mblanke <9078342+mblanke@users.noreply.github.com>

backend/app/models/tenant.py

@@ -1,6 +1,6 @@
 from sqlalchemy import Column, Integer, String, DateTime
 from sqlalchemy.orm import relationship
-from datetime import datetime
+from datetime import datetime, timezone
 
 from app.core.database import Base
 
@@ -11,7 +11,7 @@ class Tenant(Base):
     id = Column(Integer, primary_key=True, index=True)
     name = Column(String, unique=True, index=True, nullable=False)
     description = Column(String, nullable=True)
-    created_at = Column(DateTime, default=datetime.utcnow)
+    created_at = Column(DateTime, default=lambda: datetime.now(timezone.utc))
 
     # Relationships
     users = relationship("User", back_populates="tenant")