actions: build docs only in the upstream repo (not in private forks)

This should stop contributors receiving the "deployment failed" e-mails.

Signed-off-by: Jaroslav Škarvada <jskarvad@redhat.com>

.github/workflows/pages.yml

@@ -18,6 +18,7 @@ concurrency:
 
 jobs:
   build:
+    if: ${{ github.repository == 'redhat-performance/tuned' }}
     runs-on: ubuntu-latest
     steps:
       - name: Checkout the master branch
@@ -39,6 +40,7 @@ jobs:
         uses: actions/upload-pages-artifact@v4
 
   deploy:
+    if: ${{ github.repository == 'redhat-performance/tuned' }}
     environment:
       name: github-pages
       url: ${{ steps.deployment.outputs.page_url }}