Add UTF-8 encoding to file open operation

[2rtfm]

Specify UTF-8 encoding when opening the collection file.
The collection file specified 'utf-8' when writing, but no encoding was specified when reading.

    def save_to_disk(self, path: Path) -> None:
        """Save the request model to a YAML file."""
        content = self.model_dump(exclude_defaults=True, exclude_none=True)
        yaml_content = dump(
            content,
            None,
            sort_keys=False,
            allow_unicode=True,
        )
        path.parent.mkdir(parents=True, exist_ok=True)
        path.write_text(yaml_content, encoding="utf-8")

def load_request_from_yaml(file_path: str) -> RequestModel:
    """Load a request model from a YAML file.

    Args:
        file_path: The path to the YAML file.

    Returns:
        RequestModel: The request model loaded from the YAML file.
    """
    with open(file_path, "r") as file:
        data = load(file, Loader=Loader)
        return RequestModel(**data, path=Path(file_path))