[requirements-dev.txt]: Update pytest

Update pytest from `>=7.0, <8.0` to `>=8.0, <9.0`.

Author: andthum

requirements-dev.txt

@@ -20,6 +20,6 @@ flake8-rst-docstrings >=0.2.6, <1.0
 isort >=5.0, <6.0
 pep8-naming >=0.1, <1.0
 pre-commit >=3.0, <4.0
-pytest >=7.0, <8.0
+pytest >=8.0, <9.0
 shellcheck-py >=0.1, <1.0
 shfmt-py >=3.0, <4.0