Fix macOS build: install Pillow for icon conversion

Author: Deadpool2000

.github/workflows/build_and_release.yml

@@ -100,6 +100,7 @@ jobs:
           python -m pip install --upgrade pip
           pip install -r requirements.txt
           pip install pyinstaller
+          pip install Pillow
 
       # --- Windows Build ---
       - name: Build Windows