build: fix prepublish step

[jkusa]

Npm publish failed on this error:

> ember-arg-types@1.1.0 prepublishOnly
> ember ts:precompile


error TS2688: Cannot find type definition file for 'ember__test-helpers'.
  The file is in the program because:
    Entry point for implicit type library 'ember__test-helpers'

node_modules/ember-resolver/index.d.ts:1:10 - error TS2614: Module '"@ember/owner"' has no exported member 'Resolver'. Did you mean to use 'import Resolver from "@ember/owner"' instead?

1 import { Resolver as ResolverContract } from "@ember/owner";
           ~~~~~~~~