Update bleach to 3.1.3

[pyup-bot]

This PR updates bleach from 3.1.1 to 3.1.3.

Changelog

3.1.3

--------------------------------

**Security fixes**

None

**Backwards incompatible changes**

None

**Features**

* Add relative link to code of conduct. (442)

* Drop deprecated 'setup.py test' support. (507)

* Fix typo: curren -> current in tests/test_clean.py (504)

* Test on PyPy 7

* Drop test support for end of life Python 3.4

**Bug fixes**

None

3.1.2

--------------------------------

**Security fixes**

* ``bleach.clean`` behavior parsing embedded MathML and SVG content
with RCDATA tags did not match browser behavior and could result in
a mutation XSS.

Calls to ``bleach.clean`` with ``strip=False`` and ``math`` or
``svg`` tags and one or more of the RCDATA tags ``script``,
``noscript``, ``style``, ``noframes``, ``iframe``, ``noembed``, or
``xmp`` in the allowed tags whitelist were vulnerable to a mutation
XSS.

This security issue was confirmed in Bleach version v3.1.1. Earlier
versions are likely affected too.

Anyone using Bleach <=v3.1.1 is encouraged to upgrade.

https://bugzilla.mozilla.org/show_bug.cgi?id=1621692

**Backwards incompatible changes**

None

**Features**

None

**Bug fixes**

None

Links

• PyPI: https://pypi.org/project/bleach
• Changelog: https://pyup.io/changelogs/bleach/
• Repo: https://github.com/mozilla/bleach
• Docs: https://pythonhosted.org/bleach/