fix(security): update http-proxy-middleware to ^0.20.0

Author: afriestad

package.json

@@ -41,7 +41,7 @@
     "file-loader": "^1.1.6",
     "fs-extra": "^6.0.1",
     "html-webpack-plugin": "^4.0.0-alpha.2",
-    "http-proxy-middleware": "^0.17.4",
+    "http-proxy-middleware": "^0.20.0",
     "mini-css-extract-plugin": "^0.4.0",
     "minimist": "1.2.0",
     "postcss-flexbugs-fixes": "^3.3.0",