chore: update GitHub Actions workflow pyinstaller-build.yml

Author: xc407

.github/workflows/pyinstaller-build.yml

@@ -66,6 +66,12 @@ jobs:
           python -m pip install --upgrade pip
           pip install poetry==2.0.1
 
+      - name: Install UPX on macOS
+        if: runner.os == 'macOS'
+        run: |
+          brew update
+          brew install upx
+
       - name: Install dependencies
         run: |
           cd backend