add support for polars.Series

[gdementen]

Not really a bug, given that I never tested that nor announced support but an annoying oversight.

>>> pl.Series('test', [1, 2, 3])
 File "C:\usr\devel\larray-editor\larray_editor\editor.py", line 1130, in set_current_array
    self.sql_widget.update_completer_options(self.data, selected=array)
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\usr\devel\larray-editor\larray_editor\sql.py", line 104, in update_completer_options
    col_names_set.update(set(data[table_name].collect_schema().names()))
                             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
AttributeError: 'Series' object has no attribute 'collect_schema'