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.
<details>
<summary>Changelog</summary>

*Sourced from [bleach's changelog](https://github.com/mozilla/bleach/blob/master/CHANGES).*

> Version 3.1.1 (February 13th, 2020)
> -----------------------------------
> 
> **Security fixes**
> 
> * ``bleach.clean`` behavior parsing ``noscript`` tags did not match
>   browser behavior.
> 
>   Calls to ``bleach.clean`` allowing ``noscript`` and one or more of
>   the raw text tags (``title``, ``textarea``, ``script``, ``style``,
>   ``noembed``, ``noframes``, ``iframe``, and ``xmp``) were vulnerable
>   to a mutation XSS.
> 
>   This security issue was confirmed in Bleach versions v2.1.4, v3.0.2,
>   and v3.1.0. Earlier versions are probably affected too.
> 
>   Anyone using Bleach <=v3.1.0 is highly encouraged to upgrade.
> 
>   https://bugzilla.mozilla.org/show_bug.cgi?id=1615315
> 
> **Backwards incompatible changes**
> 
> None
> 
> **Features**
> 
> None
> 
> **Bug fixes**
> 
> None
> 
> Bleach changes
> ==============
</details>
<details>
<summary>Commits</summary>

- [`0d88dd8`](https://github.com/mozilla/bleach/commit/0d88dd83e425c4ba381d5b83fe61bfae5bbbd627) Update for v3.1.1 release
- [`996cde7`](https://github.com/mozilla/bleach/commit/996cde7a2439a2323f9c4b2567c8b8449d393351) fix bug 1615315
- See full diff in [compare view](https://github.com/mozilla/bleach/compare/v3.1.0...v3.1.1)
</details>
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</details>

Looks like bleach is up-to-date now, so this is no longer needed.