Actions: use ditto instead of zip to package app

With the introduction of the Sparkle Project for auto updates,
the packaging process has to be changed to preserve symlinks.
Zip destroys them resulting in a broken code signature.
Ditto aisms to fix this problem.

Author: Artur

.github/scripts/archive.sh

@@ -33,7 +33,7 @@ fi
 echo "Signature is correct. Packing app."
 
 cd $BUILD_PATH/
-zip -r "$APP_NAME.zip" "$APP_NAME"
+ditto -c -k --sequesterRsrc --keepParent "$APP_NAME" "$APP_NAME.zip"
 
 mv "$APP_NAME.zip" ../