Update pytest requirement from <8.2,>=6.2.5 to >=6.2.5,<8.4 (#1116)

Updates the requirements on [pytest](https://github.com/pytest-dev/pytest) to permit the latest version.
- [Release notes](https://github.com/pytest-dev/pytest/releases)
- [Changelog](https://github.com/pytest-dev/pytest/blob/main/CHANGELOG.rst)
- [Commits](pytest-dev/pytest@6.2.5...8.3.2)

---
updated-dependencies:
- dependency-name: pytest
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

requirements/testing_without_asyncio.txt

@@ -1,4 +1,4 @@
 # pip install -r requirements/testing_without_asyncio.txt
-pytest>=6.2.5,<8.2        # https://github.com/tornadoweb/tornado/issues/3375
+pytest>=6.2.5,<8.4        # https://github.com/tornadoweb/tornado/issues/3375
 pytest-cov>=3,<6
 black==22.8.0             # Until we drop Python 3.6 support, we have to stay with this version