Remove code style section from CONTRIBUTING.md

The section describing the use of Black for code formatting has been removed from the contributing guidelines. Contributors are no longer instructed to format code with Black before submitting pull requests.

Author: codelion

CONTRIBUTING.md

@@ -19,14 +19,6 @@ source env/bin/activate  # On Windows: env\Scripts\activate
 pip install -e ".[dev]"
 ```
 
-## Code Style
-
-We follow the [Black](https://black.readthedocs.io/) code style. Please format your code before submitting a pull request:
-
-```bash
-black openevolve tests examples
-```
-
 ## Pull Request Process
 
 1. Create a new branch for your feature or bugfix: `git checkout -b feat-your-feature-name`