Trigger Zygisk modules service.sh in parallel

For scripts in late_start service mode, they should be executed in
parallel, as explained in the official docs:

https://github.com/topjohnwu/Magisk/blob/master/docs/guides.md#boot-scripts

module/src/service.sh

@@ -15,7 +15,7 @@ if [ "$(which magisk)" ]; then
       if [ -f "$file/service.sh" ]; then
         cd "$file"
         log -p i -t "zygisk-sh" "Manually trigger service.sh for $file"
-        sh "$(realpath ./service.sh)"
+        sh "$(realpath ./service.sh)" &
         cd "$MODDIR"
       fi
     fi