Every modern operating system accepts forward slash paths. It's been a long time since there was any need for things like Python's os.path.join() or special file path knowledge in config files to convert slashes to backlashes on Windows. You can just use forward slashes everywhere and not worry about it.
The one exception on Windows may be paths in a CMD.EXE command line, where / may be confused for a switch character, but I would think a config file should not be passing paths on a command line but instead passing them directly into a program - and then the forward slash will work fine.
The one exception on Windows may be paths in a CMD.EXE command line, where / may be confused for a switch character, but I would think a config file should not be passing paths on a command line but instead passing them directly into a program - and then the forward slash will work fine.