Update auto-publish.yml

[GitHub will no longer support the Ubuntu 20.04 runner image starting from April 1, 2025](actions/runner-images#11101). That PR  updates the actions to use ubuntu-latest instead

Author: caribouW3

.github/workflows/auto-publish.yml

@@ -6,7 +6,7 @@ on:
 jobs:
   main:
     name: Build, Validate and Deploy
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v2
       - uses: w3c/spec-prod@v2