Update MongoDB driver

package.json

@@ -30,7 +30,7 @@
     "koa-router": "^7.4.0",
     "koa-static": "^5.0.0",
     "later": "^1.2.0",
-    "mongodb": "^3.2.6",
+    "mongodb": "^3.6.0",
     "parsimmon": "^1.13.0",
     "seedrandom": "^3.0.1",
     "yaml": "^1.6.0",
@@ -47,7 +47,7 @@
     "@types/koa-router": "^7.0.42",
     "@types/koa-static": "^4.0.1",
     "@types/mithril": "^2.0.0",
-    "@types/mongodb": "^3.1.31",
+    "@types/mongodb": "^3.5.25",
     "@types/parsimmon": "^1.10.0",
     "@types/seedrandom": "^2.4.28",
     "@types/svgo": "^1.2.1",