Bump bleach from 3.1.2 to 3.1.4

Bumps [bleach](https://github.com/mozilla/bleach) from 3.1.2 to 3.1.4.
- [Release notes](https://github.com/mozilla/bleach/releases)
- [Changelog](https://github.com/mozilla/bleach/blob/master/CHANGES)
- [Commits](https://github.com/mozilla/bleach/compare/v3.1.2...v3.1.4)

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

requirements.txt

@@ -3,7 +3,7 @@ astor==0.8.1
 attrs==19.3.0
 backcall==0.1.0
 base58==2.0.0
-bleach==3.1.2
+bleach==3.1.4
 blinker==1.4
 boto3==1.11.14
 botocore==1.14.14