Yes, A_Camera is right, please upload it as .txt or zip it and upload the .zip file.
The forum not allowing a few different extensions by default and some of them we already changed to allow, but some we don't want to, like exacutables,
because we would like to avoid the distribution of any viruses or anything like that via the attachments.
So, that some file extensions can't be uploaded is just for safety, but as said you can rename the file and upload it, then it is not direct distribution of viruses even if the file has a virus the downloader has to rename it before executing the code, so it is still safer.