Update testing.yml

Revert back to ubuntu-22.04 because of disconnection of self hosted runner.

Author: nedsouza

.github/workflows/testing.yml

@@ -23,7 +23,7 @@ env:
 jobs:
   docs:
     name: Documentation
-    runs-on: self-hosted
+    runs-on: ubuntu-22.04
     steps:
       - uses: actions/checkout@v3
       - uses: actions/setup-python@v4