Update composer.json

release 5.21.5

1. You can set currency_pair as empty string for finished orders or trades query
2. Add margin and cross margin max transferable API support
3. Add futures position closes history query with time range support
4. Add withdraw fees on multiple chains

add order book update ts and cross margin account history

fix inconsistent version

fix invalid auto repay enum values

add spot auto order API; trade time in spot currency pair

add margin auto repay; support transferring to sub user's futures acc…

…ount

add position close pagination, futures order book id, /wallet/fee and…

… withdrawal chain support

return etf in ticker

add etf info in spot currency pair