[Security] Bump bleach from 3.1.0 to 3.1.1

Bumps [bleach](https://github.com/mozilla/bleach) from 3.1.0 to 3.1.1. **This update includes a security fix.**
- [Release notes](https://github.com/mozilla/bleach/releases)
- [Changelog](https://github.com/mozilla/bleach/blob/master/CHANGES)
- [Commits](mozilla/bleach@v3.1.0...v3.1.1)

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

Author: dependabot-preview[bot]

requirements.txt

@@ -1,7 +1,7 @@
 apipkg==1.5
 atomicwrites==1.3.0
 attrs==18.2.0
-bleach==3.1.0
+bleach==3.1.1
 certifi==2019.6.16
 cffi==1.12.3
 chardet==3.0.4