fix dolfinx-tests.yml to reference main dolfinx (#758)

* fix dolfinx-tests.yml to reference main dolfinx

* retrigger checks

Author: sclaus2

.github/workflows/dolfinx-tests.yml

@@ -10,7 +10,7 @@ on:
     inputs:
       dolfinx_ref:
         description: "DOLFINx branch or tag"
-        default: "sclaus2/add-void-to-kernels"
+        default: "main"
         type: string
       basix_ref:
         description: "Basix branch or tag"
@@ -54,7 +54,7 @@ jobs:
         with:
           path: ./dolfinx
           repository: FEniCS/dolfinx
-          ref: sclaus2/add-void-to-kernels
+          ref: main
       - name: Get DOLFINx source (specified branch/tag)
         if: github.event_name == 'workflow_dispatch'
         uses: actions/checkout@v4