only run zizmor workflow on workflow changes (#295)

Author: joshuadavidthomas

.github/workflows/zizmor.yml

@@ -3,8 +3,12 @@ name: zizmor 🌈
 on:
   push:
     branches: [main]
+    paths:
+      - ".github/workflows/**"
   pull_request:
     branches: ["*"]
+    paths:
+      - ".github/workflows/**"
 
 jobs:
   zizmor: