Update Miner Hashrate Data Type from int to long

[tsuyohase]

Description

This pull request updates the miner's hashrate data type from int to long to accommodate larger values and prevent potential overflow issues.

Changes Made

• Modified the type of hashrate data in the genMiningPower and getGenesisMinter functions in Main.java.

Note

In the getGenesisMinter method, random.nextDouble is used internally, which may cause precision loss. This should be taken into account when dealing with very high hashrate values.