Msgpack maps with object keys support needed for proper `LedgerStateDelta` decoding

## Problem

The `LedgerStateDelta` object as returned from algod has the field `Txleases` which is a map with an object key, as show in https://github.com/algorand/go-algorand/blob/8e2e2e4f4f714e40d6156ed77cbd1b4b4763d11a/ledger/ledgercore/statedelta.go#L105

Unfortunately if this object is present, this SDK will be unable to decode any part of the msgpack state delta, since object keys are not supported by our msgpack library, https://github.com/algorand/msgpack-javascript.

## Solution

Modify and release a new version of https://github.com/algorand/msgpack-javascript with support for decoding & encoding maps with object keys. Then this SDK can use the new version of that library to properly encode & decode `LedgerStateDelta`s.