fix: package.json & package-lock.json to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JS-POSTCSS-1090595

Author: snyk-bot

package-lock.json

@@ -39,7 +39,7 @@
 		"moment-strftime": "^0.5.0",
 		"node-sass": "^4.14.1",
 		"node-sass-utils": "^1.1.2",
-		"postcss": "^8.2.8",
+		"postcss": "^8.2.10",
 		"react": "^16.14.0",
 		"react-dom": "^16.8.1",
 		"react-helmet": "^5.2.0",