fix:arrow style bug

package.json

@@ -1,6 +1,6 @@
 {
   "name": "vue-json-viewer",
-  "version": "2.2.0",
+  "version": "2.2.1",
   "description": "vuejs展示json的组件",
   "main": "vue-json-viewer.js",
   "files": [
@@ -66,10 +66,10 @@
     "file-loader": "^1.1.5",
     "html-webpack-plugin": "^3.2.0",
     "mini-css-extract-plugin": "^0.5.0",
-    "node-sass": "^4.5.3",
+    "node-sass": "^4.12.0",
     "optimize-css-assets-webpack-plugin": "^5.0.1",
     "postcss-loader": "^3.0.0",
-    "sass-loader": "^6.0.6",
+    "sass-loader": "^7.1.0",
     "style-loader": "^0.19.0",
     "uglifyjs-webpack-plugin": "^2.1.2",
     "url-loader": "^0.6.2",