Update build.yml

Enable workflow dispatch to allow manually invoking the build.  This is particularly useful for debugging/diagnosing issues.

Author: compnerd

.github/workflows/build.yml

@@ -7,6 +7,7 @@ on:
     paths:
       - '**/*.swift'
       - '.github/workflows/build.yml'
+  workflow_dispatch:
 
 jobs:
   build: