Update GitHub Actions workflow to use new spec path

Author: alexander-vyh

.github/workflows/build.yml

@@ -34,7 +34,7 @@ jobs:
         pip install pyinstaller PyQt6
 
     - name: Build application
-      run: pyinstaller --clean fileshift.spec
+      run: pyinstaller --clean packaging/fileshift.spec
 
     - name: Create DMG
       run: |