Export all items from cluster

[jacksturt]

In version 2.13, if you copy the example_ws_usage.ts code, both PythCluster and getPythClusterApiUrl are not defined. This is because they are not exported in the index.ts. This request adds those exports.

[guibescos]

Looks good to me, I've been successful with import {PythCluster} from "@pythnetwork/client/lib/cluster"; but having it in index.ts makes sense

[jacksturt]

I also updated the changelog, but the npm version command isn't working for me.

[guibescos]

Can you bump the package version in package.json and rerun npm install and commit package-lock.json

[jacksturt]

Updated!