fix(contracts): assume no zero address for beneficiary address in `ProtocolFee` fuzz test (#4781)

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solidity/test/hooks/ProtocolFee.t.sol

@@ -73,6 +73,7 @@ contract ProtocolFeeTest is Test {
     }
 
     function testSetBeneficiary(address beneficiary) public {
+        vm.assume(beneficiary != address(0));
         vm.expectEmit(true, true, true, true);
         emit ProtocolFee.BeneficiarySet(beneficiary);
         fees.setBeneficiary(beneficiary);