ci: improve step run conditions

.woodpecker/cd.yml

@@ -2,7 +2,6 @@
 
 when:
   event: [push, manual]
-  branch: main
 
 variables:
   secrets: &secrets
@@ -16,14 +15,14 @@ variables:
 steps:
   - name: build/yarn
     image: node:18
-    # when:
-    #  - path:
-    #     exclude: ['_meta/**']
     commands:
       - yarn install
       - yarn build
 
   - name: publish/s3
+    depends_on: [ build/yarn ]
+    when:
+      - branch: main
     image: amazon/aws-cli:2.15.50
     commands:
       - aws s3 sync --delete ./dist s3://$${S3_BUCKET}/
@@ -31,6 +30,9 @@ steps:
       - <<: *secrets
 
   - name: publish/cloudfront
+    depends_on: [ publish/s3 ]
+    when:
+      - branch: main
     image: amazon/aws-cli:2.15.50
     commands:
       - aws cloudfront create-invalidation --distribution-id $${CLOUDFRONT_DISTRIBUTION} --paths '/*'