use ncc to build single file dist

Rather than including node_modules in the repository, build a single
file containing everything needed using @vercel/ncc. The file can be
rebuilt using npm run build.

Author: haarg

action.yml

@@ -44,4 +44,4 @@ inputs:
 
 runs:
   using: "node16"
-  main: "index.js"
+  main: "dist/index.js"