Documentation tests with dependency version requirements are incorrectly skipped

[KostaIlic2]

Tech Debt

Several tests that used to pass (at least for some matrix cases) now always get skipped. The tests are

src/nitypes/_arguments.py::nitypes._arguments.arg_to_float SKIPPED (...) [ 0%]
src/nitypes/_arguments.py::nitypes._arguments.is_dtype SKIPPED (coul...) [ 0%]
src/nitypes/_arguments.py::nitypes._arguments.validate_dtype SKIPPED [ 0%]
src/nitypes/complex/init.py::nitypes.complex SKIPPED (could not ...) [ 0%]

The root cause are changes in pytest-doctestplus behavior introduced in 1.6.0 and not fully rectified in 1.7.0.

I will separately propose a workaround, but that workaround will be much more verbose and contain code duplication, making it worse than the original. The workaround will give us two choices:

1. Put the workaround in place, and keep this technical debt to put the code back the way it was after the root issue gets fixed.
2. Live with limited coverage until the root cause gets fixed.

AB#3703865

[bkeryan]

@KostaIlic2 is there anything left to do to uptake the fix from scientific-python/pytest-doctestplus#319 ?