Bump bleach from 1.5.0 to 3.1.4

Bumps [bleach](https://github.com/mozilla/bleach) from 1.5.0 to 3.1.4.
- [Release notes](https://github.com/mozilla/bleach/releases)
- [Changelog](https://github.com/mozilla/bleach/blob/master/CHANGES)
- [Commits](mozilla/bleach@v1.5...v3.1.4)

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

Author: dependabot[bot]

requirements.txt

@@ -1,5 +1,5 @@
 absl-py==0.7.1
-bleach==1.5.0
+bleach==3.1.4
 h5py==2.9.0
 html5lib==0.9999999
 imutils==0.5.2