Update dependency pytest to v9

Author: renovate[bot]

pyproject.toml

@@ -40,7 +40,7 @@ dev = [
     "mike>=2.0.0",
     "mypy>=0.990",
     "pymdown-extensions>=10.0.1",
-    "pytest>=8.0.0,<9",
+    "pytest>=9,<10",
     "pytest-asyncio>=0.20.3",
     "pytest-cov>=4.0.0",
     "pytest-factoryboy>=2.5.0",