Bump mongodb-download-url to 0.6.4 (#198)

Author: addaleax

package.json

@@ -31,7 +31,7 @@
     "get-mongodb-version": "^2.0.1",
     "lodash.defaults": "^4.2.0",
     "lodash.difference": "^4.1.1",
-    "mongodb-download-url": "^0.6.0",
+    "mongodb-download-url": "^0.6.4",
     "mongodb-version-list": "^1.0.0",
     "semver": "^5.3.0",
     "tildify": "^2.0.0",