lxml - security update

It was discovered that clean_html() function of lxml (pythonic bindings
for the libxml2 and libxslt libraries) performed insufficient
sanitisation for some non-printable characters. This could lead to
cross-site scripting.

For the stable distribution (wheezy), this problem has been fixed in
version 2.3.2-1+deb7u1.

For the testing distribution (jessie), this problem has been fixed in
version 3.3.5-1.

For the unstable distribution (sid), this problem has been fixed in
version 3.3.5-1.

We recommend that you upgrade your lxml packages.