Disable stale workflow on forks

Author: andyw8

.github/workflows/close_stale_issues_and_prs.yml

@@ -10,6 +10,7 @@ permissions:
 jobs:
   stale:
     runs-on: ubuntu-latest
+    if: github.repository == 'Shopify/ruby-lsp'
     steps:
       - uses: actions/stale@5f858e3efba33a5ca4407a664cc011ad407f2008 # v10.1.0
         with: