refactor: remove unused '_slasher' constructor parameter

The '_slasher' parameter was not utilized within the contract, enhancing clarity by simplifying the constructor.

Author: neutiyoo

src/slashers/VetoableSlasher.sol

@@ -20,8 +20,7 @@ contract VetoableSlasher is SlasherBase {
 
     constructor(
         IAllocationManager _allocationManager,
-        ISlashingRegistryCoordinator _slashingRegistryCoordinator,
-        address _slasher
+        ISlashingRegistryCoordinator _slashingRegistryCoordinator
     ) SlasherBase(_allocationManager, _slashingRegistryCoordinator) {}
 
     function initialize(address _vetoCommittee, address _slasher) external virtual initializer {