fix UpdateBankAccount (#35749)

* trolled

* fun

* fuck me

Content.Shared/Cargo/Components/BankClientComponent.cs

@@ -1,4 +1,3 @@
-using Content.Shared.Cargo;
 using Robust.Shared.GameStates;
 
 namespace Content.Shared.Cargo.Components;
@@ -23,4 +22,4 @@ public sealed partial class BankClientComponent : Component
 /// Raised on an entity with <see cref="BankClientComponent"/> when the bank's balance is updated.
 /// </summary>
 [ByRefEvent]
-public record struct BankBalanceUpdatedEvent(EntityUid Station, int Balance);
+public readonly record struct BankBalanceUpdatedEvent(EntityUid Station, int Balance);