Address failing build

[jeetparikh]

The forge build command was failing with the following error

Error: Compiler run failed:
Error (9582): Member "Multicalled" not found or not visible after argument-dependent lookup in type(contract GuardedMulticaller).
  --> test/multicall/GuardedMulticaller.t.sol:74:14:
   |
74 |         emit GuardedMulticaller.Multicalled(signer, ref, targets, data, deadline);

It was unable access the event the original contract. Based on the pattern used in other tests, defined the event in the test itself which fixes the issue