Update from subscription-transport-ws to graphql-ws

The **subscription-transport-ws** repo uses the the _graphql-ws_ protocol to manage websocket connections to the graphql server. The subscription-transport-ws library has been deprecated and is no longer maintained so we should move away from using this.

Instead, users are encouraged to move to the **graphql-ws** library which uses the _graphql-transport-ws_ protocol.

Some details on how to switch are given here: https://www.apollographql.com/docs/apollo-server/data/subscriptions/#updating-subscription-clients

This should only require changes in the src/connection/coniql.ts file.