try to parallelise updating submodules

Author: hjwp

.github/workflows/tests.yml

@@ -40,7 +40,7 @@ jobs:
         shell: bash
         run: |
           sed -i '[email protected]:_https://github.com/_' .gitmodules
-          git submodule update --init --recursive
+          git submodule status | cut -d" " -f2 | xargs git submodule update --init
 
       - name: setup Git
         shell: bash