Alias reconnect -> connect for replica set clients

Calling `reconnect` on a replica set won't actually work, because the alias is not called again after `connect` is overridden in `Mongo::MongoReplicaSetClient`. So instead `Mongo::MongoReplicaSetClient#reconnect` calls `Mongo::MongoClient#connect` which naturally errors, as it's a replica set connection and not a single server one.

Just a quick one line fix.