fix(package): update dotenv to version 8.1.0

Closes #88

Author: greenkeeper[bot]

package.json

@@ -49,7 +49,7 @@
     "body-parser": "1.16.0",
     "casual": "1.5.9",
     "dataloader": "1.2.0",
-    "dotenv": "2.0.0",
+    "dotenv": "8.1.0",
     "express": "4.14.1",
     "express-session": "1.14.1",
     "graphql": "0.9.0",