Intermittent test failures - lru / hypothesis

[madwort]

the tests/lib/test_lru_dict.py intermittently fails in CI with a message like:

Unreliable test timings! On an initial run, this test took 251.43ms, which exceeded the deadline of 200.00ms, but on a subsequent run it took 43.48 ms, which did not. If you expect this sort of variability in your test timings, consider turning deadlines off for this test by setting deadline=None.

I think this test is run in six environments per PR/merge, increasing the chances that one of the tests will hit a slow case & fail due to this. Maybe we could turn off (or increase the timeout) for this test?