Update weekly-mainline-sync.yml

Restrict job to the ROCm/rocprofiler-systems repository. 
No need to run on forks.

.github/workflows/weekly-mainline-sync.yml

@@ -6,6 +6,7 @@ on:
 
 jobs:
   promote-stg-to-main:
+    if: github.repository == 'ROCm/rocprofiler-systems'
     runs-on: ubuntu-latest
     name: Promote Staging to Mainline
     steps: