fix: package.json to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JS-PATHTOREGEXP-8482416

Author: snyk-bot

package.json

@@ -34,7 +34,7 @@
     "@angular/upgrade": "5.0.1",
     "app-module-path": "2.2.0",
     "core-js": "2.5.1",
-    "express": "4.16.2",
+    "express": "4.21.2",
     "jquery": "3.5.0",
     "lodash": "4.17.15",
     "rxjs": "5.5.2",