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

Author: renovate-bot

package-lock.json

@@ -33,7 +33,7 @@
   "devDependencies": {
     "@ht2-labs/semantic-release": "1.1.68",
     "@ht2-labs/typescript-project": "2.0.34",
-    "@types/dotenv": "4.0.3",
+    "@types/dotenv": "6.1.1",
     "@types/lodash": "4.14.127",
     "@types/mocha": "5.2.6",
     "@types/mongodb": "3.1.26",