Use only main as additional fetch ref

Author: zklaus

.github/workflows/linux_job_v2.yml

@@ -48,7 +48,6 @@ on:
         description: 'Additional refs to fetch, space separated'
         default: |
           refs/heads/main
-          refs/heads/viable/strict
         type: string
       checkout-mode:
         description: 'Mode of checkout; one of "normal", "blobless", "treeless".'