update_schema().update_column() does not update required property for list elements

[mukul-mpac]

Bug Report

Description

When using update_schema().update_column() to update the required property of list elements, the field type updates successfully but the required property does not change.

Environment

• PyIceberg version: 0.10.0
• Python version: 3.12.12
• Platform: macOS

Root Cause

Located in pyiceberg/table/update/schema.py:112 in the _ApplyChanges.list() method:

return ListType(element_id=list_type.element_id, element=element_type, 
                element_required=list_type.element_required)  # Always uses original value

The method always uses the original element_required value instead of checking if the element field has been updated in self._updates.

Minimal Reproduction

from pyiceberg.types import ListType, StringType

# Create table with list field where elements are optional (element_required=False)
with iceberg_table.update_schema() as update_schema:
    update_schema.add_column(
        path="test_list_primitive",
        field_type=ListType(element_type=StringType(), element_required=False),
    )

# Try to update element to be required
with iceberg_table.update_schema(allow_incompatible_changes=True) as update_schema:
    update_schema.update_column(
        path=("test_list_primitive", "element"),
        required=True,  # This doesn't work
    )

# Check schema - element_required is still False
field = iceberg_table.schema().find_field("test_list_primitive")
print(field.field_type.element_required)  # Still False, should be True

Expected Behavior

The element_required property should be updated to True.

Actual Behavior

The element_required property remains False (unchanged).

Proposed Fix

def list(self, list_type: ListType) -> ListType:
    element_type = self._visit_type(list_type.element_type)
    element_required = list_type.element_required
    
    # Check if element field has been updated
    if update := self._updates.get(list_type.element_id):
        element_required = update.required
    
    return ListType(
        element_id=list_type.element_id,
        element=element_type,
        element_required=element_required
    )

Workaround

Drop and recreate the list field:

# Step 1: Drop
with iceberg_table.update_schema(allow_incompatible_changes=True) as update_schema:
    update_schema.delete_column("test_list_primitive")

# Step 2: Recreate with element_required=True
with iceberg_table.update_schema(allow_incompatible_changes=True) as update_schema:
    update_schema.add_column(
        path="test_list_primitive",
        field_type=ListType(element_type=StringType(), element_required=True),
    )

Additional Notes

A similar issue likely exists for MapType.value_required in the map() method of the same class.