Fix typing in the stub

Co-authored-by: Noureldin <noureldinyosri@gmail.com>

Author: jarthurgross

tunits/core/__init__.pyi

@@ -334,7 +334,7 @@ class ValueArray(Generic[ValueType2], WithUnit):
     def to_proto(self, msg: tunits_pb2.ValueArray | None = None) -> tunits_pb2.ValueArray: ...
     def __init__(self, data: Any, unit: Any = None) -> None: ...
     def allclose(self, other: ValueArray | Value, *args: Any, **kwargs: float) -> bool: ...
-    def unique(self) -> ValueArray: ...
+    def unique(self: ArrayType) -> ArrayType: ...
     def __array__(self, dtype: DTypeLike = None) -> NDArray[Any]: ...
     def __array_wrap__(self, out_arr: NDArray[Any], context: Any = None) -> NDArray[Any]: ...
     def __copy__(self: ArrayType) -> ArrayType: ...