build: limit update authors CI scope

PR-URL: https://github.com/nodejs/node/pull/40219
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Zijian Liu <lxxyxzj@gmail.com>
Reviewed-By: Qingyu Deng <i@ayase-lab.com>
Reviewed-By: Darshan Sen <raisinten@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>

.github/workflows/authors.yml

@@ -8,6 +8,7 @@ on:
 
 jobs:
   authors_update:
+    if: github.repository == 'nodejs/node'
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v2