Pytest generates a warning, see [1]. The patch fixes it. 1. https://docs.pytest.org/en/latest/deprecations.html#configuring-hook-specs-impls-using-markers

The testcase `test_link` passed on FreeBSD 12.2 and becom broken on FreeBSD 14.0. The test failed with an error below: File "/tmp/cirrus-ci-build/unreliablefs/tests/test_unreliablefs.py", line 262, in test_link os.link(name1, name2) OSError: [Errno 5] Input/output error: '/tmp/pytest-of-root/pytest-0/test_link0/mnt/testfile_14' -> '/tmp/pytest-of-root/pytest-0/test_link0/mnt/testfile_15'

`nanosleep()` fails if `.tv_nsec` is larger than 999999999, so duration must be distributed between `.tv_sec` and `.tv_nsec`. Duration also needs to be stored in `unsigned long long` to be able to store values of more than ~4 seconds.

Follows up commit a0b3fda7 ("ci: remove testing with macOS on Cirrus CI")

py38-pip -> py39-pip [1], python38 -> python39 [2] 1. https://www.freshports.org/devel/py-pip 2. https://www.freshports.org/lang/python39

"Intel-based Big Sur and High Sierra instances will stop working on January 1st 2023." [1] 1. https://cirrus-ci.org/blog/2022/11/08/sunsetting-intel-macos-instances/

Fixes #108