fix: package.json to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JS-HANDLEBARS-534478

Author: snyk-bot

package.json

@@ -19,7 +19,7 @@
      "axios": "0.18.0",
      "chownr": "1.0.1",
      "eslint-utils": "1.3.1",
-     "handlebars": "4.0.12",
+     "handlebars": "4.5.2",
      "lodash": "4.17.11",
      "mime": "1.4.1",
      "mixin-deep": "1.3.1",