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

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JS-NODESASS-542662

Author: snyk-bot

package-lock.json

@@ -25,7 +25,7 @@
     "font-awesome": "^4.7.0",
     "jquery": "^3.4.1",
     "lodash": "^4.17.14",
-    "node-sass": "^4.12.0",
+    "node-sass": "^4.13.1",
     "package.json": "^2.0.1",
     "prop-types": "^15.7.2",
     "react": "^16.8.6",