Update pytest requirement from ^7 to >=7,<9 (#29)

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@7.0.0...8.0.0)

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

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

pyproject.toml

@@ -34,7 +34,7 @@ numpy = "^1.21"  # For NumPy Typing.
 optional = true
 
 [tool.poetry.group.test.dependencies]
-pytest = "^7"
+pytest = ">=7,<9"
 
 [build-system]
 requires = ["poetry_core"]