chore: 🤖 upgrade api addon to ember lts 3.20

addons/api/tests/dummy/app/app.js

@@ -1,7 +1,7 @@
 import Application from '@ember/application';
 import Resolver from 'ember-resolver';
 import loadInitializers from 'ember-load-initializers';
-import config from './config/environment';
+import config from 'dummy/config/environment';
 
 export default class App extends Application {
   modulePrefix = config.modulePrefix;

addons/api/tests/dummy/app/router.js

@@ -1,5 +1,5 @@
 import EmberRouter from '@ember/routing/router';
-import config from './config/environment';
+import config from 'dummy/config/environment';
 
 export default class Router extends EmberRouter {
   location = config.locationType;

addons/api/tests/dummy/config/ember-cli-update.json

@@ -0,0 +1,20 @@
+{
+  "schemaVersion": "1.0.0",
+  "packages": [
+    {
+      "name": "ember-cli",
+      "version": "3.20.2",
+      "blueprints": [
+        {
+          "name": "addon",
+          "outputRepo": "https://github.com/ember-cli/ember-addon-output",
+          "codemodsSource": "ember-addon-codemods-manifest@1",
+          "isBaseBlueprint": true,
+          "options": [
+            "--no-welcome"
+          ]
+        }
+      ]
+    }
+  ]
+}

addons/api/tests/dummy/config/targets.js

@@ -6,7 +6,7 @@ const browsers = [
   'last 1 Safari versions',
 ];
 
-const isCI = !!process.env.CI;
+const isCI = Boolean(process.env.CI);
 const isProduction = process.env.EMBER_ENV === 'production';
 
 if (isCI || isProduction) {

addons/api/tests/test-helper.js

@@ -1,5 +1,5 @@
-import Application from '../app';
-import config from '../config/environment';
+import Application from 'dummy/app';
+import config from 'dummy/config/environment';
 import { setApplication } from '@ember/test-helpers';
 import { start } from 'ember-qunit';
 

addons/api/tests/unit/mixins/adapter-build-url-test.js

@@ -1,4 +1,5 @@
 import RESTAdapter from '@ember-data/adapter/rest';
+/* eslint-disable-next-line ember/no-mixins */
 import AdapterBuildURLMixin from 'api/mixins/adapter-build-url';
 import { module, test } from 'qunit';
 import { setupTest } from 'ember-qunit';
@@ -8,6 +9,7 @@ module('Unit | Mixin | build-url', function (hooks) {
 
   test('it does not interfere with basic URLs', function (assert) {
     assert.expect(1);
+    /* eslint-disable-next-line ember/no-new-mixins */
     const Adapter = RESTAdapter.extend(AdapterBuildURLMixin);
     this.owner.register('adapter:adapter', Adapter);
     const adapter = this.owner.lookup('adapter:adapter');
@@ -17,6 +19,7 @@ module('Unit | Mixin | build-url', function (hooks) {
 
   test('it does not interfere with namespaced URLs', function (assert) {
     assert.expect(1);
+    /* eslint-disable-next-line ember/no-new-mixins */
     const Adapter = RESTAdapter.extend(AdapterBuildURLMixin, {
       namespace: 'api/v1',
     });
@@ -28,6 +31,7 @@ module('Unit | Mixin | build-url', function (hooks) {
 
   test('it can prepend a prefix', function (assert) {
     assert.expect(1);
+    /* eslint-disable-next-line ember/no-new-mixins */
     const Adapter = RESTAdapter.extend(AdapterBuildURLMixin, {
       urlPrefix() {
         return '/foo/bars';
@@ -41,6 +45,7 @@ module('Unit | Mixin | build-url', function (hooks) {
 
   test('it can append a suffix', function (assert) {
     assert.expect(1);
+    /* eslint-disable-next-line ember/no-new-mixins */
     const Adapter = RESTAdapter.extend(AdapterBuildURLMixin, {
       urlSuffix() {
         return ':method';