fix(jest): downgrate vue-jest to v3

pending by vuejs/vue-jest#241

Author: clarkdo

packages/cna-template/template/frameworks/ava/test/specs/Logo.spec.js

@@ -4,5 +4,5 @@ import Logo from '@/components/Logo.vue'
 
 test('is a Vue instance', (t) => {
   const wrapper = mount(Logo)
-  t.is(wrapper.isVueInstance(), true)
+  t.is(wrapper.vm, true)
 })

packages/cna-template/template/frameworks/jest/package.json

@@ -4,9 +4,10 @@
   },
   "devDependencies": {
     "@vue/test-utils": "^1.0.0-beta.33",
+    "babel-core": "7.0.0-bridge.0",
     "babel-jest": "^25.5.1",
     "jest": "^25.5.2",
     "ts-jest": "^25.4.0",
-    "vue-jest": "^4.0.0-beta.2"
+    "vue-jest": "^3.0.4"
   }
 }

packages/cna-template/template/frameworks/jest/test/Logo.spec.js

@@ -4,6 +4,6 @@ import Logo from '@/components/Logo.vue'
 describe('Logo', () => {
   test('is a Vue instance', () => {
     const wrapper = mount(Logo)
-    expect(wrapper.isVueInstance()).toBeTruthy()
+    expect(wrapper.vm).toBeTruthy()
   })
 })

packages/create-nuxt-app/test/snapshots/index.test.js.md

@@ -2222,9 +2222,10 @@ Generated by [AVA](https://avajs.dev).
       },
       devDependencies: {
         '@vue/test-utils': '^1.0.0-beta.33',
+        'babel-core': '7.0.0-bridge.0',
         'babel-jest': '^25.5.1',
         jest: '^25.5.2',
-        'vue-jest': '^4.0.0-beta.2',
+        'vue-jest': '^3.0.4',
       },
       private: true,
       scripts: {

packages/create-nuxt-app/test/snapshots/index.test.js.snap

@@ -5,6 +5,9 @@
   "lockFileMaintenance": {
     "enabled": true
   },
+  "ignoreDeps": [
+    "vue-jest"
+  ],
   "packageRules": [
     {
       "packagePatterns": ["nuxt"],