bug: get file base name error in `PromptBuilder` when the operating system is Windows

[betnevs]

class PromptBuilder:

    def __init__(
        self,
        source_file_path: str,
        test_file_path: str,
        code_coverage_report: str,
        included_files: str = "",
        additional_instructions: str = "",
        failed_test_runs: str = "",
        language: str = "python",
    ):
        self.source_file_name = source_file_path.split("/")[-1]
        self.test_file_name = test_file_path.split("/")[-1]
       ......

this code could potentially have issues on a Windows system. In Windows, the path separator is a backslash \, not a forward slash /. Therefore, if run this code on a Windows system, split("/") may not correctly split the file path.