eslint conflict with ember-cli

By default, ember-cli adds the following to `.eslintrc.js`:
```js
// node files
{
env: {
browser: false,
node: true,
},
files: [
'ember-cli-build.js',
'testem.js',
'blueprints/*/index.js',
'config/**/*.js',
'lib/*/index.js',
],
parserOptions: {
ecmaVersion: 2015,
sourceType: 'script',
},
},
```
That means the output to be copied to `config/deprecation-workflow.js` should have something like
```js
/* eslint-env browser */
```
or
```js
/* globals window */
```
at the top.

Or, alternatively, ember-cli-deprecation-workflow should add
```js
excludedFiles: [ 'config/deprecation-workflow.js' ],
```
to the relevant `overrides` section.