greedy_001 adds sets for which all the items are already covered

[yuvalregev1003]

@ccoffrin greedy_001 solution (possibly others too, haven't looked into them yet) keeps adding sets until getting full coverage. However - some sets are added for which their items are already covered by previously added sets, thus adding cost but without any value gain.
By adding the following inside the main loop: (tested in 3.10, not in earlier Python versions)

        if len(set(s.items).intersection(covered)) == len(set(s.items)):
            continue

this can be avoided