Doc: remove the invalid type variables of typing.TextIO and BinaryIO

[SpecLad]

They are not generic classes.

---

📚 Documentation preview 📚: https://cpython-previews--142642.org.readthedocs.build/

[python-cla-bot]

All commit authors signed the Contributor License Agreement.

[miss-islington-app]

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

[miss-islington-app]

Sorry, @SpecLad and @JelleZijlstra, I could not cleanly backport this to 3.13 due to a conflict.
Please backport using cherry_picker on command line.

cherry_picker fa1ac9070c7525cab69c043ca2259e6d86357fb3 3.13

[bedevere-app]

GH-142643 is a backport of this pull request to the 3.14 branch.

[bedevere-bot]

⚠️⚠️⚠️ Buildbot failure ⚠️⚠️⚠️

Hi! The buildbot s390x Fedora Stable Refleaks 3.14 (tier-3) has failed when building commit e014076.

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/1776/builds/737) and take a look at the build logs.
4. Check if the failure is related to this commit (e014076) 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/1776/builds/737

Failed tests:

• test_external_inspection

Failed subtests:

• test_only_active_thread - test.test_external_inspection.TestGetStackTrace.test_only_active_thread

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

==

Click to see traceback logs

Traceback (most recent call last):
  File "/home/buildbot/buildarea/3.14.cstratak-fedora-stable-s390x.refleak/build/Lib/test/test_external_inspection.py", line 1246, in test_only_active_thread
    self.assertEqual(
    ~~~~~~~~~~~~~~~~^
        len(gil_traces), 1, "Should have exactly one GIL holder"
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    )
    ^
AssertionError: 0 != 1 : Should have exactly one GIL holder

[StanFromIreland]

We don't need to backport to 3.13:

cpython/Doc/library/typing.rst

Lines 2773 to 2775 in dc12380

	.. class:: IO
	TextIO
	BinaryIO