update ubuntu image to latest

Author: rdmueller

.github/workflows/gh-pages.yml

@@ -9,7 +9,7 @@ on:
 
 jobs:
   deploy:
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-latest
     concurrency:
       group: ${{ github.workflow }}-${{ github.ref }}
     env:
@@ -27,4 +27,4 @@ jobs:
         #        if: ${{ github.ref == 'refs/heads/main' }}
         with:
           github_token: ${{ secrets.GITHUB_TOKEN }}
-          publish_dir: ./public
+          publish_dir: ./public