Upgrade Yarn

package.json

@@ -1,14 +1,14 @@
 {
     "devDependencies": {
-        "@symfony/webpack-encore": "^0.28.2",
-        "bootstrap": "^4.4.1",
-        "copy-webpack-plugin": "^5.1.1",
+        "@symfony/webpack-encore": "^0.31.0",
+        "bootstrap": "^4.5.3",
+        "copy-webpack-plugin": "^6.2.1",
         "core-js": "^3.0.0",
         "jquery": "^3.5.0",
-        "node-sass": "^4.14.0",
+        "node-sass": "^4.14.1",
         "popper.js": "^1.16.1",
         "regenerator-runtime": "^0.13.2",
-        "sass-loader": "7.0.1",
+        "sass-loader": "8.0.0",
         "webpack-notifier": "^1.6.0"
     },
     "license": "UNLICENSED",
@@ -20,6 +20,6 @@
         "build": "encore production --progress"
     },
     "dependencies": {
-        "lodash": "4.17.19"
+        "lodash": "4.17.20"
     }
 }