v2.2.0

• add support for cw1155 (#11)
• when doing check for cw20, remove the casting of the contract address to lowercase. this was necessary previously as cosmwasm-std contained a bug that made it not able to raise an error when the address is not normalized. the bug has since been fixed, meaning the force-casting is no longer necessary
• empty asset lists now stringify to [] instead of an empty string (``)
• introduce a new function AssetUnchecked::from_sdk_str for creating an AssetUnchecked instance from a cosmos-sdk coin string, which is the format {amount}{denom}