chore(package): update @types/dotenv to version 6.1.1

Closes #38

Author: greenkeeper[bot]

package.json

@@ -56,7 +56,7 @@
     "@types/chai-http": "^3.0.4",
     "@types/cookie-parser": "^1.4.1",
     "@types/cors": "^2.8.3",
-    "@types/dotenv": "^4.0.2",
+    "@types/dotenv": "^6.1.1",
     "@types/errorhandler": "0.0.32",
     "@types/express": "^4.11.1",
     "@types/jasmine": "~2.8.6",