build(deps-dev): update pytest requirement from <8 to <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@1.0.0b3...8.0.0)

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

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

pyproject.toml

@@ -121,7 +121,7 @@ test = [
 ]
 testing = [
   "coverage~=7.3",
-  "pytest<8",
+  "pytest<9",
   "pytest-cov<5",
   "pytest-env<2",
   "pytest-mock<4",