fix: remove FnOnceSnapImpl

corelib/src/ops/function.cairo

@@ -23,15 +23,6 @@ impl FnOnceImpl<T, Args, +Destruct<T>, +Fn<T, Args>> of FnOnce<T, Args> {
     }
 }
 
-/// An implementation of `FnOnce` when `Fn` is implemented and the receiver is by-reference.
-/// Makes sure we can always pass an `Fn` to a function that expects an `FnOnce`.
-impl FnOnceSnapImpl<T, Args, +Destruct<T>, +Fn<T, Args>> of FnOnce<@T, Args> {
-    type Output = Fn::<T, Args>::Output;
-    fn call(self: @T, args: Args) -> Self::Output {
-        Fn::call(self, args)
-    }
-}
-
 /// The version of the call operator that takes a by-snapshot receiver.
 ///
 /// Instances of `Fn` can be called multiple times.