Silence NonInteractiveExampleWarning in test_unary

[jakevdp]

The .example() call leads to a number of warnings in the test suite:

/.../array-api-tests/array_api_tests/test_special_cases.py:1253: NonInteractiveExampleWarning: The `.example()` method is good for exploring strategies, but should only be used interactively.  We recommend using `@given` for tests - it performs better, saves and replays failures to avoid flakiness, and reports minimal examples. (strategy: from_dtype(float64, min_value=0.0, max_value=13_407_807_929_942_595_611_008_317_640_802_934_282_464_207_265_959_107_021_466_054_756_094_376_573_581_619_054_852_612_241_927_956_455_650_759_996_398_703_782_412_109_633_178_814_162_067_569_513_603_268_608, exclude_min=True))
    in_value = case.cond_from_dtype(xp.float64).example()

I don't see an easy way for @given to be used here, but silencing the warning will make it more friendly to downstream CI jobs.

[asmeurer]

These special case tests are doing some strange things with hypothesis. It's not clear to me if there aren't other downsides to using example here, or even if we can be sure that just drawing one example is going to definitely do what we want. IMO we should either draw multiple examples normally, like we used to, or just hard-code a specific example, rather than just assuming that a single hypothesis draw is going to work.

At any rate, we do need to clear all the annoying warnings that are currently printed. I will add a comment to the code here and merge this.