Docs: fix spelling of 'test case' in unittest documentation

[cliff688]

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📚 Documentation preview 📚: https://cpython-previews--134137.org.readthedocs.build/

[python-cla-bot]

All commit authors signed the Contributor License Agreement.

[miss-islington-app]

Thanks @picnixz for merging it 🌮🎉.. I'm working now to backport this PR to: 3.13, 3.14.
🐍🍒⛏🤖

[bedevere-app]

3.14 branch.

[bedevere-app]

3.13 branch.

[bedevere-bot]

⚠️⚠️ Buildbot failure ⚠️⚠️

Hi! The buildbot AMD64 FreeBSD Refleaks 3.14 (tier-3) has failed when building commit b43e1d0.

What do you need to do:

1. Don't panic.
2. Check the buildbot page in the devguide if you don't know what the buildbots are or how they work.
3. Go to the page of the buildbot that failed (https://buildbot.python.org/#/builders/1800/builds/57) and take a look at the build logs.
4. Check if the failure is related to this commit (b43e1d0) or if it is a false positive.
5. If the failure is related to this commit, please, reflect that on the issue and make a new Pull Request with a fix.

You can take a look at the buildbot page here:

https://buildbot.python.org/#/builders/1800/builds/57

Test leaking resources:

• test_events: references
• test_events: memory blocks

Summary of the results of the build (if available):

==

Click to see traceback logs

Traceback (most recent call last):
  File "/buildbot/buildarea/3.14.ware-freebsd.refleak/build/Lib/test/support/__init__.py", line 829, in gc_collect
    gc.collect()
ResourceWarning: unclosed <socket.socket fd=9, family=2, type=1, proto=6, laddr=('127.0.0.1', 49001), raddr=('127.0.0.1', 49002)>
Task was destroyed but it is pending!
task: <Task pending name='Task-3372' coro=<BaseSelectorEventLoop._accept_connection2() done, defined at /buildbot/buildarea/3.14.ware-freebsd.refleak/build/Lib/asyncio/selector_events.py:217> wait_for=<Future pending cb=[Task.task_wakeup()]>>
Warning -- Unraisable exception
Exception ignored while calling deallocator <function _SelectorTransport.__del__ at 0x83927c7d0>:
Traceback (most recent call last):
  File "/buildbot/buildarea/3.14.ware-freebsd.refleak/build/Lib/asyncio/selector_events.py", line 873, in __del__
    _warn(f"unclosed transport {self!r}", ResourceWarning, source=self)
ResourceWarning: unclosed transport <_SelectorSocketTransport closing fd=9>
k


Traceback (most recent call last):
  File "/buildbot/buildarea/3.14.ware-freebsd.refleak/build/Lib/test/support/__init__.py", line 829, in gc_collect
    gc.collect()
ResourceWarning: unclosed <socket.socket fd=9, family=2, type=1, proto=6, laddr=('127.0.0.1', 50335), raddr=('127.0.0.1', 50336)>
Task was destroyed but it is pending!
task: <Task pending name='Task-3845' coro=<BaseSelectorEventLoop._accept_connection2() done, defined at /buildbot/buildarea/3.14.ware-freebsd.refleak/build/Lib/asyncio/selector_events.py:217> wait_for=<Future pending cb=[Task.task_wakeup()]>>
Warning -- Unraisable exception
Exception ignored while calling deallocator <function _SelectorTransport.__del__ at 0x840f27110>:
Traceback (most recent call last):
  File "/buildbot/buildarea/3.14.ware-freebsd.refleak/build/Lib/asyncio/selector_events.py", line 873, in __del__
    _warn(f"unclosed transport {self!r}", ResourceWarning, source=self)
ResourceWarning: unclosed transport <_SelectorSocketTransport closing fd=9>
k