fix: Correct output datatype of dt.year and dt.mil (#23646)

Author: coastalwhite

crates/polars-plan/src/plans/aexpr/function_expr/datetime.rs

@@ -82,8 +82,7 @@ impl IRTemporalFunction {
     pub(super) fn get_field(&self, mapper: FieldsMapper) -> PolarsResult<Field> {
         use IRTemporalFunction::*;
         match self {
-            Millennium | Century => mapper.with_dtype(DataType::Int8),
-            Year | IsoYear => mapper.with_dtype(DataType::Int32),
+            Millennium | Century | Year | IsoYear => mapper.with_dtype(DataType::Int32),
             OrdinalDay => mapper.with_dtype(DataType::Int16),
             Month | Quarter | Week | WeekDay | Day | Hour | Minute | Second => {
                 mapper.with_dtype(DataType::Int8)

py-polars/tests/unit/operations/test_index_of.py

@@ -179,6 +179,7 @@ def test_groupby() -> None:
 )
 # The examples are cases where this test previously caught bugs:
 @example([], [], [None])
+@pytest.mark.slow
 def test_randomized(
     list1: list[int | None], list2: list[int | None], list3: list[int | None]
 ) -> None:

py-polars/tests/unit/sql/test_cast.py

@@ -185,6 +185,7 @@ def test_cast_errors(values: Any, cast_op: str, error: str) -> None:
     assert None in res.to_series()
 
 
+@pytest.mark.may_fail_cloud  # reason: eager construct to_struct
 def test_cast_json() -> None:
     df = pl.DataFrame({"txt": ['{"a":[1,2,3],"b":["x","y","z"],"c":5.0}']})