Bump csh_ldap to 2.2.1 to include comparison fixes

Pinning version that allows set differencing. This will make count of
voting members accurate, since it pulls in liam_middlebrook/csh_ldap#23.

Author: mxmeinhold

requirements.txt

@@ -2,7 +2,7 @@ alembic~=0.9.8
 astroid~=2.2.5
 blinker~=1.4
 click~=6.7
-csh-ldap~=2.2
+git+git://github.com/mxmeinhold/csh_ldap@c441add834405761758bea981fd5286f2abcaf93#egg=csh_ldap
 Flask~=1.1.0
 Flask-Migrate~=2.1.1
 Flask-Gzip~=0.2