Update GitHub actions build.yml

(cherry picked from commit 9c20206)

.github/workflows/build.yml

@@ -1,10 +1,9 @@
 name: Build
 on:
   push:
-    branches:
-      - master
   pull_request:
     types: [opened, synchronize, reopened]
+  workflow_dispatch:
 jobs:
   build:
     name: Build