fix: packages/css/package.json to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JS-ANSIREGEX-1583908
- https://snyk.io/vuln/SNYK-JS-GLOBPARENT-1016905
- https://snyk.io/vuln/SNYK-JS-INFLIGHT-6095116
- https://snyk.io/vuln/SNYK-JS-UNSETVALUE-2400660

packages/css/package.json

@@ -13,7 +13,7 @@
   },
   "devDependencies": {
     "cross-env": "^7.0.3",
-    "gulp": "^4.0.2"
+    "gulp": "^5.0.0"
   },
   "files": [
     "npm-shrinkwrap.json",