fix: package.json to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JS-RAILROADDIAGRAMS-6282875

package.json

@@ -36,7 +36,7 @@
     "is-string-and-not-blank": "0.0.2",
     "lodash": "4.17.21",
     "mailauth": "2.3.3",
-    "mailparser": "3.5.0",
+    "mailparser": "3.6.0",
     "mailsplit": "5.3.2",
     "ms": "2.1.3",
     "mx-connect": "1.2.0",