fix: site/package.json to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JS-SOCKJS-575261
- https://snyk.io/vuln/SNYK-JS-YARGSPARSER-560381

Author: snyk-bot

site/package.json

@@ -11,7 +11,7 @@
     "react-dom": "^16.13.1",
     "react-hash-handler": "^0.1.11",
     "react-indicators": "^0.3.14",
-    "react-scripts": "^3.4.1",
+    "react-scripts": "^3.4.2",
     "react-scroll-trigger": "^0.6.3",
     "react-target-scroller": "^0.1.14",
     "react-timecode": "^1.1.22",