Update pytest requirement from <8,>=6 to >=6,<9

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@6.0.0...8.0.0)

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

Signed-off-by: dependabot[bot] <[email protected]>

pyproject.toml

@@ -24,7 +24,7 @@ tests = [
     "mypy >= 1.3,< 2.0",
     "pycodestyle ~= 2.6",
     "PyHamcrest ~= 2.0",
-    "pytest >= 6,< 8",
+    "pytest >= 6,< 9",
     "pytest-asyncio ~= 0.14",
 ]