message: Add CHANGELOG entries for Tendermint 0.34
diff: - @cosmjs/tendermint-rpc: Remove trivial helpers `getTxEventHeight`,
  `getHeaderEventHeight` and `getBlockEventHeight` because they don't do
  anything else than accessing an object member.
  +- @cosmjs/tendermint-rpc: Add support for connecting to Tendermint RPC 0.34.
  +- @cosmjs/tendermint-rpc: Make `TxEvent.index` optional and deprecate it because
  + it is not set anymore in Tendermint 0.34.
  - @cosmjs/utils: Add `assertDefined`.
  - @cosmjs/faucet: Rename binary from `cosmwasm-faucet` to `cosmos-faucet`.
  