Added unit test for backend

Author: AjitPadhi-Microsoft

content-gen/src/backend/requirements-dev.txt

@@ -6,6 +6,9 @@
 pytest>=8.0.0
 pytest-asyncio>=0.23.0
 pytest-cov>=5.0.0
+pytest-mock>=3.14.0
+httpx>=0.27.0
+quart-cors>=0.7.0
 
 # Code Quality
 black>=24.0.0