update CI workflow to use self-hosted Ubuntu 22.04 for documentation build

Author: thomas-saigre

.github/workflows/ci.yml

@@ -12,7 +12,7 @@ on:
 jobs:
 
   build_docs:
-    runs-on: ubuntu-22.04
+    runs-on: self-ubuntu-22.04
     name: Build, Install, Package documentation
     if: "!contains(github.event.head_commit.message, 'docs skip')"
     steps: