Merge pull request #238 from cmu-delphi/dsweber2-styler-patch

CI: styler only on PRs or button press

Author: dajmcdon

.github/workflows/styler.yml

@@ -1,7 +1,8 @@
 # Workflow derived from https://github.com/r-lib/actions/tree/v2/examples
 # Need help debugging build failures? Start at https://github.com/r-lib/actions#where-to-find-help
 on:
-  push:
+  workflow_dispatch:
+  pullrequest:
     paths:
       [
         "**.[rR]",