Stage the nuclei sync with a pathspec git accepts

git would not expand [12][0-9][0-9][0-9] as a pathspec, so the job did its
work and then died on the commit. Everything it touches is already tracked
apart from nuclei.json, so stage tracked changes and name that one file.

.github/workflows/sync_nuclei.yml

@@ -31,7 +31,8 @@ jobs:
         run: |
           git config user.name 'CVE-BOT'
           git config user.email '[email protected]'
-          git add -- nuclei.json '[12][0-9][0-9][0-9]'
+          git add -u
+          git add -- nuclei.json
           if git diff --cached --quiet; then
             echo "No changes to commit"
             exit 0