Bump bleach from 3.1.0 to 3.1.4

Bumps [bleach](https://github.com/mozilla/bleach) from 3.1.0 to 3.1.4.
- [Release notes](https://github.com/mozilla/bleach/releases)
- [Changelog](https://github.com/mozilla/bleach/blob/master/CHANGES)
- [Commits](mozilla/bleach@v3.1.0...v3.1.4)

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

requirements.txt

@@ -14,7 +14,7 @@ markdown==3.1.1
 tweepy==3.8.0
 bitlyapi==0.1.1
 coverage==5.0.3
-bleach==3.1.0
+bleach==3.1.4
 ordereddict==1.1
 jsmin==2.2.2
 psycopg2==2.8.4