Add dummy test for self hosted GitHub runners (espressif#5521)

* Add dummy test for self hosted GitHub runners

Author: tomassebestik

.github/workflows/test_selfhosted_runner.yml

@@ -0,0 +1,27 @@
+name: Test Github action on self hosted RPI runnes
+
+on:
+  push:
+    branches:
+    - master
+  pull_request:
+
+jobs:
+  build:
+    name: Dummy test - self hosted GHR
+    runs-on: self-hosted
+    steps:
+      - name: Check out repo
+        uses: actions/checkout@v2
+      - name: Test message 1
+        run: echo "This is test message"
+      - name: Test message 2
+        run: echo "This is test message2"
+      - name: List directory
+        run: ls
+      - name: Create copy of README
+        run: cp README.md README2.md
+      - name: Read README2
+        run: cat README2.md
+      - name: Delete README2
+        run: rm README2.md