Fix CI workflow: Update to use modern pyproject.toml dev dependencies

- Replace dev_dependencies.txt with 'pip install -e .[dev]'
- Ensures pytest and other dev tools are installed from pyproject.toml
- Aligns CI with modern Python packaging standards

Author: suyask-msft

.github/workflows/python-package.yml

@@ -28,7 +28,7 @@ jobs:
       run: |
         python -m pip install --upgrade pip
         python -m pip install flake8 black build
-        if [ -f dev_dependencies.txt ]; then pip install -r dev_dependencies.txt; fi
+        python -m pip install -e .[dev]
     
     - name: Check format with black
       continue-on-error: true  # TODO: fix detected formatting errors and remove this line.