fix: BridgeEmulator/web-ui-src/package.json & BridgeEmulator/web-ui-src/package-lock.json to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JS-SERIALIZEJAVASCRIPT-536840

Author: snyk-bot

BridgeEmulator/web-ui-src/package-lock.json

@@ -21,7 +21,7 @@
     "react-dom": "16.3.3",
     "react-emotion": "9.1.3",
     "react-powerplug": "^1.0.0-rc.1",
-    "react-scripts": "^3.0.1",
+    "react-scripts": "^3.3.0",
     "snyk": "^1.230.5"
   },
   "devDependencies": {