Pass PR URL instead of body to xKAN-meta_testing action (#2372)

.github/workflows/validate.yml

@@ -33,6 +33,6 @@ jobs:
                   EVENT_BEFORE: ${{ github.event.before }}
               with:
                   source: commits
-                  pull request body: ${{ github.event.pull_request.body }}
+                  pull request url: ${{ github.event.pull_request.url }}
             - name: Chmod cached files so actions/cache can read them
               run: sudo chmod -R a+r .cache