added defaults in workflow, removed unnecessary chmod

.gitea/workflows/update-child-repos.yaml

@@ -7,12 +7,15 @@ on:
     branches:
       - main
 
+defaults:
+  run:
+    shell: bash
+
 jobs:
   update:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
-      - run: chmod +x update.sh
       - run: |
           export GITEA_TOKEN=${{ secrets.GITEA_TOKEN }}
           git config --global credential.helper store