Bump bleach from 3.1.0 to 3.1.1 (#116)

Bumps [bleach](https://github.com/mozilla/bleach) from 3.1.0 to 3.1.1.
- [Release notes](https://github.com/mozilla/bleach/releases)
- [Changelog](https://github.com/mozilla/bleach/blob/master/CHANGES)
- [Commits](https://github.com/mozilla/bleach/compare/v3.1.0...v3.1.1)

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

requirements.txt

@@ -1,6 +1,6 @@
 attrs==19.1.0
 bitarray==0.9.3
-bleach==3.1.0
+bleach==3.1.1
 cattrs-3.8==0.9.1
 certifi==2018.11.29
 chardet==3.0.4