Update samson.yml

open source needs ubuntu-latest

Author: everops-john

.github/workflows/samson.yml

@@ -4,7 +4,7 @@ on:
     branches: master
 jobs:
   samson:
-    runs-on: zendesk-stable
+    runs-on: ubuntu-latest
     if: github.ref == 'refs/heads/master'
     steps:
     - name: Notify Samson