Drop unused imports.

diffoscope/changes.py

diffoscope/comparators/binary.py

diffoscope/comparators/bzip2.py

diffoscope/comparators/cbfs.py

diffoscope/comparators/deb.py

diffoscope/comparators/debian.py

diffoscope/comparators/device.py

diffoscope/comparators/dex.py

diffoscope/comparators/directory.py

diffoscope/comparators/fsimage.py

diffoscope/comparators/gzip.py

diffoscope/comparators/libarchive.py

diffoscope/comparators/macho.py

diffoscope/comparators/squashfs.py

diffoscope/comparators/symlink.py

diffoscope/comparators/tar.py

diffoscope/comparators/utils.py

diffoscope/comparators/xz.py

diffoscope/difference.py

diffoscope/presenters/html.py