Update icon for PyInstaller build and remove old PNG file

Author: vigneshsaravanakumar404

.github/workflows/build-release.yml

@@ -31,7 +31,7 @@ jobs:
 
       - name: Build EXE with PyInstaller
         run: |
-          python -m PyInstaller --onefile --windowed --name="AWS_EC2_VPN" --icon=Assets/icon.png --paths=Client --distpath=dist Client/main.py
+          python -m PyInstaller --onefile --windowed --name="AWS_EC2_VPN" --icon=Assets/icon.ico --paths=Client --distpath=dist Client/main.py
 
       - name: Get version from tag
         id: get_version