createBlockFilter 
Creates a Filter to listen for new block hashes that can be used with getFilterChanges.
Usage 
ts
import { publicClient } from './client'
const filter = await publicClient.createBlockFilter() 
// { id: "0x345a6572337856574a76364e457a4366", type: 'block' }
ts
import { createPublicClient, http } from 'viem'
import { mainnet } from 'viem/chains'
export const publicClient = createPublicClient({
  chain: mainnet,
  transport: http()
})