Make some Mexc.API.V1.Contract.TickerData fields nullable#89

gryumov merged 1 commit intobhftbootcamp:release/v0.35.0bhftbootcamp/CryptoExchangeAPIs.jl:release/v0.35.0from

IlyaVshivtsev:hotfix/mexc-contract-tickerIlyaVshivtsev/CryptoExchangeAPIs.jl:hotfix/mexc-contract-tickerCopy head branch name to clipboard