Drop unused intbitset dep

Signed-off-by: Philippe Ombredanne <pombredanne@nexb.com>

Author: pombredanne

setup.cfg

@@ -41,7 +41,6 @@ install_requires =
     attrs >= 18.1, !=20.1.0
     Beautifulsoup4 >= 4.0.0
     click >= 6.7, !=7.0
-    intbitset >= 2.3.0
     requests >= 2.7.0
     saneyaml >= 0.5.2
     text_unidecode >= 1.0