build: skip test-internet run on forks

Do not run test-internet scheduled GitHub Action on forks.

PR-URL: https://github.com/nodejs/node/pull/44054
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
Reviewed-By: Juan José Arboleda <soyjuanarbol@gmail.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Darshan Sen <raisinten@gmail.com>

.github/workflows/test-internet.yml

@@ -29,6 +29,7 @@ permissions:
 
 jobs:
   test-internet:
+    if: github.repository == 'nodejs/node'
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v3