Add Unicode support for SBDF path handling #80

[vrane-tibco]

This change updates the _pathlike_to_fileptr function to handle Unicode file paths across platforms.(Fix for #80)

1. On Windows:

    Uses _wfopen() instead of fopen() for file opening.
    
    Converts Python str and bytes objects to wchar_t* to support non-ASCII paths (e.g., filenames with Japanese, Chinese, or other Unicode characters).
    
    Avoids reliance on system locale settings or the "Beta: UTF-8" flag.
   

2. On POSIX systems:

    Continues using fopen() with UTF-8 encoded char*.
   
    Utilizes PyUnicode_FSConverter() to convert Python str objects appropriately.