package.json: Add author email

Hopefully avoids lintian error:

The package is of bad quality

The installation of a package which violates the quality standards isn't allowed. This could cause serious problems on your computer. Please contact the person or organisation who provided this package file and include the details beneath.

Lintian check results for /home/mongo/Projects/compass/dist/mongodb-compass-dev_1~6~0-dev_amd64.deb:
E: mongodb-compass-dev: maintainer-address-missing MongoDB Inc.

package.json

@@ -6,7 +6,8 @@
   "version": "1.6.0-dev",
   "main": "src/main.js",
   "author": {
-    "name": "MongoDB Inc."
+    "name": "MongoDB Inc.",
+    "email": "compass@mongodb.com"
   },
   "license": "UNLICENSED",
   "private": true,