Update pytest requirement from >=7.0.0 to >=9.1.0

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...9.1.0)

---
updated-dependencies:
- dependency-name: pytest
  dependency-version: 9.1.0
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

requirements.txt

@@ -1,6 +1,6 @@
 # Core evolution system
 openai>=1.0.0          # LLM client (OpenAI-compatible: Mistral, Ollama, etc.)
-pytest>=7.0.0          # Test execution for generated code
+pytest>=9.1.0          # Test execution for generated code
 flake8>=6.0.0          # Linting for generated code
 
 # Development