Revert file name to app.py

Signed-off-by: Maysun J Faisal <maysunaneek@gmail.com>

Author: maysunfaisal

__main__.py app.py__main__.py renamed to app.py

@@ -19,4 +19,4 @@ RUN \
   fi
 
 # Specify the command to run on container start
-CMD [ "python", "." ]
+CMD [ "python", "./app.py" ]