chore(deps): update dependency @types/dotenv to v6

Author: renovate-bot

package-lock.json

@@ -33,14 +33,14 @@
   "devDependencies": {
     "@ht2-labs/semantic-release": "1.1.57",
     "@ht2-labs/typescript-project": "2.0.19",
-    "@types/dotenv": "4.0.3",
+    "@types/dotenv": "6.1.0",
     "@types/lodash": "4.14.119",
     "@types/mocha": "5.2.5",
     "@types/mongodb": "3.1.19",
     "@types/node": "8.10.39",
     "@types/source-map-support": "0.4.1",
     "assert-rejects": "0.1.1",
-    "dotenv": "5.0.1",
+    "dotenv": "6.2.0",
     "jscpd": "0.6.25",
     "mocha": "5.2.0",
     "nyc": "11.9.0",