fix(ci): build runs on every commits/deploy is only for gh-pages

Author: ryoppippi

.github/workflows/build.yml

@@ -2,13 +2,8 @@ name: Build and Deploy Jekyll site
 
 on:
   push:
-    branches:
-      - gh-pages
+  pull_request:
 
-permissions:
-  contents: read
-  pages: write
-  id-token: write
 
 jobs:
   build:
@@ -46,6 +41,11 @@ jobs:
       name: github-pages
       url: ${{ steps.deployment.outputs.page_url }}
     runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      pages: write
+      id-token: write
+    if: github.ref == 'refs/heads/gh-pages'
     steps:
       - name: Deploy to GitHub Pages
         id: deployment