Experiment with self hosted action runner

.github/workflows/main_matrix.yml

@@ -105,7 +105,7 @@ jobs:
           - board: m5stack-coreink
           - board: tbeam-s3-core
 
-    runs-on: ubuntu-latest
+    runs-on: [self-hosted, ubuntu-latest]
     steps:
       - name: Checkout code
         uses: actions/checkout@v3