refactor: Reuse .__array__ for PolarsSeries.to_numpy

- We've already got the compat handled there
- `polars` handles the rest in https://github.com/pola-rs/polars/blob/889a2a7a57be5da432b6fa854ab698bbaf1b02ff/py-polars/polars/series/series.py#L1357-L1399

Author: dangotbanned

narwhals/_polars/series.py

@@ -174,6 +174,9 @@ def replace_strict(
             raise NotImplementedError(msg)
         return self._from_native_series(ser.replace_strict(old, new, return_dtype=dtype))
 
+    def to_numpy(self, dtype: Any = None, *, copy: bool | None = None) -> _1DArray:
+        return self.__array__(dtype, copy=copy)
+
     def __array__(self: Self, dtype: Any, *, copy: bool | None) -> _1DArray:
         if self._backend_version < (0, 20, 29):
             return self._native_series.__array__(dtype=dtype)
@@ -587,10 +590,6 @@ def hist(
     def to_polars(self: Self) -> pl.Series:
         return self._native_series
 
-    # TODO @dangotbanned: review converting `copy` to a version compat argument
-    def to_numpy(self, dtype: Any = None, *, copy: bool | None = None) -> _1DArray:
-        return self.native.to_numpy()
-
     @property
     def dt(self: Self) -> PolarsSeriesDateTimeNamespace:
         return PolarsSeriesDateTimeNamespace(self)