New fixes for 1 vulnerable dependency (deep-extend) (#4507)

* fix: package.json to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/npm:lodash:20180130

Latest report for heldersepu/swagger-ui:
https://snyk.io/test/github/heldersepu/swagger-ui

* fix: package.json to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/npm:deep-extend:20180409

Latest report for heldersepu/swagger-ui:
https://snyk.io/test/github/heldersepu/swagger-ui

package.json

@@ -47,7 +47,7 @@
     "commonmark": "^0.28.1",
     "core-js": "^2.5.1",
     "css.escape": "1.5.1",
-    "deep-extend": "0.4.1",
+    "deep-extend": "0.5.1",
     "dompurify": "^1.0.4",
     "expect": "1.20.2",
     "getbase": "^2.8.2",