Bump bleach from 3.1.1 to 3.1.2

Bumps [bleach](https://github.com/mozilla/bleach) from 3.1.1 to 3.1.2.
- [Release notes](https://github.com/mozilla/bleach/releases)
- [Changelog](https://github.com/mozilla/bleach/blob/master/CHANGES)
- [Commits](mozilla/bleach@v3.1.1...v3.1.2)

Signed-off-by: dependabot[bot] <support@github.com>

frozen-requirements.txt

@@ -5,7 +5,7 @@ astroid==2.2.5
 atomicwrites==1.3.0
 attrs==19.1.0
 Babel==2.7.0
-bleach==3.1.1
+bleach==3.1.2
 blessings==1.7
 bpython==0.18
 certifi==2019.6.16