Solve the problem of incorrect amount when the transfer amount is very small

Converting an exponential number into its decimal form (https://github.com/Fenguoz/bsc-php/pull/27[)](https://github.com/Fenguoz/bsc-php/commit/8659b7af67ea9349b6a1493b97c8f3dceb811aca)

Add BEP20 parameter validation

Get balance to support decimal point parameters

Optimize

Optimize the description of README and example files

Added getTransactionByHash interface

Resolve contract transaction failure due to low gas fees

Optimize the low version of guzzle

Support PHP8+

Solve

• Solve BIP44 parameter passing format error