set git default branch in unit tests job too

Author: hjwp

.github/workflows/tests.yml

@@ -158,6 +158,13 @@ jobs:
         run: |
           make .venv/bin
 
+      - name: setup Git
+        shell: bash
+        run: |
+          git config --global user.email "[email protected]"
+          git config --global user.name "Elspeth See-Eye"
+          git config --global init.defaultBranch main
+
       - name: prep tests submodule
         shell: bash
         run: |