Websocket server doesn't have a keepAlive

[tinleym]

Summary

Reading the websocket server implementation here, I noticed that there are no keepAlive processes.

https://github.com/graphile/crystal/blob/4fe66c21bc4280315b2ae1ce5d39c7a933bb259f/grafast/grafserv/src/servers/node/index.ts

Possible Solution

Instead of directly using makeServer, graphql-ws offers a higher level useServer function, which wraps makeServer with keepAlive processes via a single parameter. If nothing else, its source could be a useful guide:

https://the-guild.dev/graphql/ws/docs/use/ws/functions/useServer