Deploy when versions.mk changes

The deploy pipeline watched a VERSION file that does not exist, so a
version bump built the image but never deployed it.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

.woodpecker/deploy.yaml

@@ -5,7 +5,7 @@ when:
         - 'config/variables/server.values.yaml'
         - '.woodpecker/deploy.yaml'
         - 'Makefile'
-        - 'VERSION'
+        - 'versions.mk'
         - 'Dockerfile'
         - '**/*.go'
     event: [push, cron, manual]