No reason to expected ufunc.types_ to be None.

[oleksandr-pavlyk]

Encountered unexpected test failure using the following test invocation:

python -m pytest \
   dpctl/tests/test_tensor_*.py \
   dpctl/tests/test_usm_ndarray_*.py \
   dpctl/tests/elementwise/test_a*.py

• Have you provided a meaningful PR description?
• Have you added a test, reproducer or referred to an issue with a reproducer?
• Have you tested your changes locally for CPU and GPU devices?
• Have you made sure that new changes do not introduce compiler warnings?
• Have you checked performance impact of proposed changes?
• If this PR is a work in progress, are you opening the PR as a draft?

[github-actions]

Deleted rendered PR docs from intelpython.github.com/dpctl, latest should be updated shortly. 🤞

[coveralls]

coverage: 91.0%. remained the same
when pulling 8d72b07 on fix-types-property-test
into 86aaede on master.

[github-actions]

Array API standard conformance tests for dpctl=0.15.1dev3=py310h15de555_44 ran successfully.
Passed: 909
Failed: 0
Skipped: 86

[ndgrigorian]

This is a good change, but it may make more sense to remove that line altogether.
It was added there to test that caching of types takes place (starts at None, is set afterward), but was malformed.

[oleksandr-pavlyk]

@ndgrigorian I have push the change to remove testing of .types_ attribute altogether, and renamed test_abs_types_prop to test_abs_types_property to stay consistent with name in test_add.py.