fix workflow branches (#18)

.github/workflows/dependency-review.yml

@@ -6,8 +6,6 @@
 # Public documentation: https://docs.github.com/en/code-security/supply-chain-security/understanding-your-software-supply-chain/about-dependency-review#dependency-review-enforcement
 name: 'Dependency Review'
 on:
-  push:
-    branches: [ main ]
   pull_request:
     branches: [ main ]