Fix builder workflow push trigger paths (#179)

The build.json has been yaml for quite a while.

Author: sairon

.github/workflows/builder.yml

@@ -9,7 +9,7 @@ on:
     branches: ["master"]
     paths:
     - Dockerfile
-    - build.json
+    - build.yaml
     - 'rootfs/**'
     - 'plugins/**'