Disable OIDC for coverage uploads from forks

This is based on the following comment:
codecov/codecov-action#1594 (comment)

Author: snejus

.github/workflows/ci.yaml

@@ -75,4 +75,4 @@ jobs:
         uses: codecov/codecov-action@v4
         with:
           files: ./coverage.xml
-          use_oidc: true
+          use_oidc: ${{ !(github.event_name == 'pull_request' && github.event.pull_request.head.repo.fork) }}