fix: adding max-parallel option to avoid lack of resources (#327)

Author: DeimerM

.github/workflows/integration-test.yml

@@ -7,6 +7,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       fail-fast: false
+      max-parallel: 1
       matrix:
         tutor_version: ['<20.0.0', '<21.0.0', 'main']
     steps: