/**
 * Adds or updates a label in the GitHub repository for a pull request.
 *
 * This function creates a label with the specified name, description, and color.
 * If a label with the same name already exists, it updates the label based on the error message.
 *
 * @param label - The name of the label to create or update.
 * @param description - The description of the label.
 * @param color - The color of the label in hexadecimal format (e.g., "FF5733").
 * @returns A promise that resolves when the label has been successfully created or updated.
 *
 * @throws {Error} If an error occurs while creating or updating the label.
 */
export declare function addPullRequestLabel(label: string, description: string, color: string): Promise<void>;