fix(test): call enableSingleRuntimeChunk() in functional test

Author: Kocal

test/functional.js

@@ -1895,6 +1895,7 @@ module.exports = {
 
             const appDir = testSetup.createTestAppDir(os.tmpdir()); // to prevent issue with Encore's .eslintrc.js
             const config = testSetup.createWebpackConfig(appDir, 'www/build', 'dev');
+            config.enableSingleRuntimeChunk();
             config.setPublicPath('/build');
             config.addEntry('main', './js/eslint');
             config.enableEslintPlugin({