improve test_copy_reduce and test_deepcopy_reduce coverage

[dslavicek]

Line 94 in copy() method and line 150 in deepcopy() method were not covered by tests. This happened because the reductor = getattr(x, "__reduce_ex__", None) at lines 88 and 144 took __reduce_ex__ from the object class which preventing reaching the else block where __reduce__ is checked.

This PR adds coverage for those two lines and by this increases branch coverage of the copy module to 100%.

printscreen of coverage check on main:

[tomasr8]

Rather than modifying existing tests, could you create new tests for the __reduce__ case?

[dslavicek]

Rather than modifying existing tests, could you create new tests for the __reduce__ case?

Since the existing tests are named test_copy_reduce and test_deepcopy_reduce it occured to me they are supposed to cover the __reduce__ case and there should be no new tests added for this.

Maybe I gave the PR a confusing name and should have named it something like "Fix test_copy_reduce and "test_deepcopy_reduce".