pip compatibility

[not-lain]

this will add pip compatible format as well as keeping backward compatibility
for people who want to test this pr before merging you can

pip install git+https://github.com/andrewdcampbell/OpenCV-Document-Scanner.git@refs/pr/20/head

or if you're working with requirements.txt you can add this to your file

opencv_document_scanner @ git+https://github.com/andrewdcampbell/OpenCV-Document-Scanner.git@refs/pr/20/head

this will also add a terminal command that can run everywhere in your computer

document-scanner