Update .rubocop.yml per migration guide

jabenninghoff · jabenninghoff · commit a5e1115b0827 · 2025-03-31T09:47:47.000-07:00
https://docs.rubocop.org/rubocop/plugin_migration_guide.html
diff --git a/.rubocop.yml b/.rubocop.yml
@@ -1,4 +1,4 @@
-require:
+plugins:
  - rubocop-rake
 
 AllCops:
