fix: package.json to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JS-NODEMAILER-1296415

package.json

@@ -43,7 +43,7 @@
     "jsonschema": "1.4.0",
     "lodash": "4.17.21",
     "mongodb": "3.6.9",
-    "nodemailer": "6.4.18",
+    "nodemailer": "6.6.1",
     "nodemailer-direct-transport": "3.3.2",
     "nodemailer-sendmail-transport": "1.0.2",
     "nodemailer-smtp-transport": "2.7.4",