Fix bug in first_n

[kordejong]

On Windows GH workflow, sometimes:

ERROR: test_overloads (algorithm.routing_operation.first_n_test.FirstNTest)
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Traceback (most recent call last):
  File "D:\a\lue\lue\lue_source\source\framework\python\test\lue_test\test_case.py", line 23, in wrapper
    test_case(self)
  File "D:\a\lue\lue\lue_source\source\framework\python\test\algorithm\routing_operation\first_n_test.py", line 28, in test_overloads
    lfr.first_n(route, max_nr_cells)
RuntimeError: this promise has no valid shared state: HPX(no_state)

[kordejong]

Segmentation fault in lue_framework_algorithm_first_n_test on orkney.