Update DOLFINx branch

.github/workflows/dolfin-tests.yml

@@ -67,6 +67,7 @@ jobs:
         with:
           path: ./dolfinx
           repository: FEniCS/dolfinx
+          ref: garth/geometry-type
       - name: Get DOLFINx source (specified branch/tag)
         if: github.event_name == 'workflow_dispatch'
         uses: actions/checkout@v2