GH Actions: Trigger build on release creation

Author: mmsinclair

.github/workflows/build.yml

@@ -2,6 +2,8 @@ name: Build validator binary
 
 on:
   workflow_dispatch:
+  release:
+    types: [created]  
 
 jobs:
   build:
@@ -59,4 +61,4 @@ jobs:
         uses: softprops/action-gh-release@v1
         if: github.event_name == 'release'
         with:
-          files: build/*
+          files: build/*