fix(deps): update dependency pytest to v9

Author: renovate[bot]

amp_demos/python/flask/pyproject.toml

@@ -7,7 +7,7 @@ requires-python = ">=3.14.0"
 dependencies = ["flask>=3.1.2,<3.2", "python-dotenv>=1.1.1,<1.2"]
 
 [project.optional-dependencies]
-dev = ["pytest>=8.4.2", "pytest-flask>=1.3.0", "black>=25.9.0", "flake8>=7.3.0"]
+dev = ["pytest>=9.0.1", "pytest-flask>=1.3.0", "black>=25.9.0", "flake8>=7.3.0"]
 
 [project.scripts]
 dev = "main:main"