Fix name dict_helper to dict_helpers

So we have the same name for everyhing

test-run/iterator_handling/dict_helpers.py

@@ -5,7 +5,7 @@ Iterator helper testing
 from typing import Any
 from corelibs.debug_handling.dump_data import dump_data
 from corelibs.iterator_handling.dict_mask import mask
-from corelibs.iterator_handling.dict_helper import set_entry
+from corelibs.iterator_handling.dict_helpers import set_entry
 
 
 def __mask():

tests/unit/iterator_handling/test_dict_helpers.py

@@ -6,7 +6,7 @@ iterator_handling.dict_helper tests
 
 from typing import Any
 import pytest
-from corelibs.iterator_handling.dict_helper import (
+from corelibs.iterator_handling.dict_helpers import (
     delete_keys_from_set,
     build_dict,
     set_entry,