CI: Use gh api to create a PR instead

gh pr create uses the GraphQL API which does not support scoped personal
access tokens. Calling the REST API through gh api directly should work.

.github/workflows/update.yaml

@@ -38,7 +38,7 @@ jobs:
           git config user.email "[email protected]"
           git commit -m "Updated prefixes by ssrfgen"
           git push -u origin HEAD
-          gh pr create -B main -H update-$(date +"%Y-%m-%d") --title "Updated prefixes by ssrfgen" --body "" --reviewer daenney
+          gh api repos/daenney/ssrf/pulls -f title='Updated prefixes by ssrfgen' -f base='main' -f head="update-$(date +'%Y-%m-%d')" -f body=''
         else
           echo "No changes to generated code"
         fi