Workflows: Try limiting the coverage-upload to the root repo.

I.e. don't run it in forks.

.github/workflows/coverage.yml

@@ -53,6 +53,7 @@ jobs:
 
   deploy-coverage:
     needs: coverage
+    if: github.repository == 'gnucash/gnucash'
     permissions:
       pages: write
       id-token: write