Update API to v6+ to support new v14 metadata

[nuke-web3]

https://github.com/substrate-developer-hub/substrate-front-end-template/blob/2bcedd13d6cfdcfb344847ade741e5a294d13fac/package.json#L18

Breaking changes to the upstream are about to be released, presently used on Rococo. API v6+ is required. To test before a formal release, we can connect to the public Rococo RPC node: rococo-rpc.polkadot.io (or spin up a rococo-local instance)

• A companion to this is needed to update to the node template

[jimmychu0807]

Close by #200