Fix build workflow

.github/workflows/build-dist.yml

@@ -1,8 +1,15 @@
+name: Build dist
+
+on:
+  push:
+    branches:
+      - main
+
 jobs:
   build-dist:
     runs-on: ubuntu-latest
 
-    steps:
+   steps:
       - name: Generate GitHub App token
         id: generate-token
         uses: tibdex/github-app-token@v2
@@ -37,9 +44,10 @@ jobs:
           git commit -m "Bump dist build" || echo "No build changes"
 
           SHA=$(git rev-parse HEAD)
+          mkdir -p dist
           echo "$SHA" > dist/commit.txt
 
           git add dist/commit.txt
           git commit -m "Update main CDN URL. (https://cdn.jsdelivr.net/gh/sparkjsdev/spark@$SHA/dist/spark.module.js)" || echo "No SHA change"
 
-          git push origin HEAD:main
+          git push origin HEAD:main