fix: package.json to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JS-LODASH-567746

Author: snyk-bot

package.json

@@ -11,7 +11,7 @@
     "chalk": "2.4.1",
     "commander": "2.9.0",
     "debug": "4.1.0",
-    "lodash": "4.17.11",
+    "lodash": "4.17.20",
     "mkdirp": "0.5.1",
     "ncp": "2.0.0",
     "prompt": "1.0.0",