Bump bleach from 3.1.1 to 3.1.2 (#122)

Bumps [bleach](https://github.com/mozilla/bleach) from 3.1.1 to 3.1.2.
- [Release notes](https://github.com/mozilla/bleach/releases)
- [Changelog](https://github.com/mozilla/bleach/blob/master/CHANGES)
- [Commits](https://github.com/mozilla/bleach/compare/v3.1.1...v3.1.2)

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

requirements.txt

@@ -2,7 +2,7 @@ appdirs==1.4.3
 args==0.1.0
 attrs==19.1.0
 bitarray==0.9.3
-bleach==3.1.1
+bleach==3.1.2
 cattrs-3.8==0.9.1
 certifi==2018.11.29
 chardet==3.0.4