Hypothesis version 6.159.0

Hypothesis has historically referred to the single execution of a test
function as an "example". However, we have in recent years tended to
call a single execution a "test case" instead, which we think is a
more precise and less overloaded term.

This release updates user-facing documentation, log messages, and
error messages to use the "test case" terminology. Some observability
fields which contain raw strings from Hypothesis might change in
format as a result.

This is not a breaking change, as we have intentionally not changed
any code APIs. In particular, "settings.max_examples" has not been
changed.

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