fix: remove __esModule

(rollup adds it)

Author: pi0

src/index.ts

@@ -4,8 +4,6 @@ export const isPerformanceSupported = () => false
 
 export const now = () => Date.now()
 
-export const __esModule = true
-
 export default {
   setupDevtoolsPlugin,
   isPerformanceSupported,

test/index.test.ts

@@ -5,6 +5,7 @@ import * as devtoolsAPI from '../src'
 describe('vue-devtools-stub', () => {
   describe('has same exports of @vue/devtools-api', () => {
     for (const key in actualDevtools) {
+      if (key === '__esModule') { continue }
       it(key, () => {
         expect(typeof (devtoolsAPI as any)[key]).toBe(typeof (actualDevtools as any)[key])
       })