title: ESLint is not a constructor
body: <p>I have made the porting to eslint-webpack-plugin and I am getting the error &quot;ESLint is not a constructor&quot;, the relevant snippet code is:</p>
  <pre><code>const ESLintPlugin = require('eslint-webpack-plugin');
  
    const plugins = [
      new webpack.DefinePlugin(productionEnvironmentVariables),
      new ESLintPlugin({
        overrideConfigFile: path.resolve(configPath, '.eslintrc.json')
      })
    ];
  </code></pre>
  <p>Any idea what is wrong? I have tried also with new ESLintPlugin() and ESLintPlugin({}).</p>
  <p>Webpack version is ^4.44.2
  Eslint version is ^6.8.0
  eslint-webpack-plugin is ^2.1.0</p>
  <p>Thank you in advance and regards.</p>