perf: simplify pandas scatter (#2154)

simplify pandas scatter

Author: MarcoGorelli

narwhals/_pandas_like/series.py

@@ -227,11 +227,8 @@ def ewm_mean(
 
     def scatter(self: Self, indices: int | Sequence[int], values: Any) -> Self:
         if isinstance(values, self.__class__):
-            # .copy() is necessary in some pre-2.2 versions of pandas to avoid
-            # `values` also getting modified (!)
-            _, values = align_and_extract_native(self, values)
             values = set_index(
-                values.copy(),
+                values._native_series,
                 self._native_series.index[indices],
                 implementation=self._implementation,
                 backend_version=self._backend_version,

tests/conftest.py

@@ -22,7 +22,7 @@
     from narwhals.typing import IntoDataFrame
     from narwhals.typing import IntoFrame
 
-MIN_PANDAS_NULLABLE_VERSION = (1, 5)
+MIN_PANDAS_NULLABLE_VERSION = (2,)
 
 # When testing cudf.pandas in Kaggle, we get an error if we try to run
 # python -m cudf.pandas -m pytest --constructors=pandas. This gives us