bumping to 7.7.0 babel/core to support babel.config.json

Author: weaverryan

package.json

@@ -25,7 +25,7 @@
   },
   "homepage": "https://github.com/symfony/webpack-encore",
   "dependencies": {
-    "@babel/core": "^7.4.0",
+    "@babel/core": "^7.7.0",
     "@babel/plugin-syntax-dynamic-import": "^7.0.0",
     "@babel/preset-env": "^7.4.0",
     "assets-webpack-plugin": "^3.9.7",