fix: package.json to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JS-JSON5-3182856

Author: snyk-bot

package.json

@@ -27,7 +27,7 @@
     "autoprefixer": "6.3.7",
     "babel-core": "6.10.4",
     "babel-eslint": "6.1.2",
-    "babel-loader": "6.2.4",
+    "babel-loader": "8.2.4",
     "babel-plugin-syntax-trailing-function-commas": "6.8.0",
     "babel-plugin-transform-class-properties": "6.10.2",
     "babel-plugin-transform-object-rest-spread": "6.8.0",
@@ -37,23 +37,23 @@
     "babel-preset-react": "6.11.1",
     "chalk": "1.1.3",
     "cross-spawn": "4.0.0",
-    "css-loader": "0.23.1",
+    "css-loader": "4.0.0",
     "eslint": "3.1.1",
-    "eslint-loader": "1.4.1",
+    "eslint-loader": "4.0.0",
     "eslint-plugin-import": "1.10.3",
     "eslint-plugin-react": "5.2.2",
     "extract-text-webpack-plugin": "1.0.1",
-    "file-loader": "0.9.0",
+    "file-loader": "6.0.0",
     "fs-extra": "^0.30.0",
-    "html-webpack-plugin": "2.22.0",
+    "html-webpack-plugin": "5.0.0",
     "json-loader": "0.5.4",
     "opn": "4.0.2",
-    "postcss-loader": "0.9.1",
+    "postcss-loader": "4.0.0",
     "rimraf": "2.5.3",
     "semver": "^5.3.0",
-    "style-loader": "0.13.1",
-    "url-loader": "0.5.7",
-    "webpack": "1.13.1",
+    "style-loader": "1.1.4",
+    "url-loader": "4.0.0",
+    "webpack": "5.0.0",
     "webpack-dev-server": "1.14.1"
   },
   "devDependencies": {