Fix import issues with o2app

Fix import issues with o2app

- Fix FromAsCasing Warning making Keywords to capital case
- Update setuptools to 78.1.1 for CVE-2025-47273
- Added PYTHONPATH environment variable for better importing

TestPlan:
PASS : Build the container image
PASS : Run a container from the image
PASS : Start pubsub with python
PASS : python /src/o2app/entrypoints/redis_eventconsumer.py
PASS : Confirm log ModuleNotFoundError: No module named 'o2app' is not present

Change-Id: I3bea247f2f1f139b7f79a1891fed277dfe05aef4
Signed-off-by: vpachchi <vineela.pachchipulusu@windriver.com>