Bump seneca from 1.4.0 to 3.9.0

Bumps [seneca](https://github.com/senecajs/seneca) from 1.4.0 to 3.9.0.
- [Release notes](https://github.com/senecajs/seneca/releases)
- [Changelog](https://github.com/senecajs/seneca/blob/master/CHANGES.md)
- [Commits](senecajs/seneca@v1.4.0...v3.9.0)

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

package.json

@@ -50,7 +50,7 @@
     "po2json": "0.4.2",
     "postgrator": "2.8.1",
     "request": "2.58.0",
-    "seneca": "1.4",
+    "seneca": "3.9",
     "seneca-auth": "1.0",
     "seneca-mail": "^0.2.2",
     "seneca-newrelic": "Wardormeur/seneca-newrelic",