Bump bleach in /experiments/invariant-risk-minimization

Bumps [bleach](https://github.com/mozilla/bleach) from 3.1.0 to 3.1.1.
- [Release notes](https://github.com/mozilla/bleach/releases)
- [Changelog](https://github.com/mozilla/bleach/blob/master/CHANGES)
- [Commits](mozilla/bleach@v3.1.0...v3.1.1)

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

experiments/invariant-risk-minimization/notebooks/requirements.txt

@@ -1,7 +1,7 @@
 appnope==0.1.0
 attrs==19.3.0
 backcall==0.1.0
-bleach==3.1.0
+bleach==3.1.1
 cycler==0.10.0
 decorator==4.4.1
 defusedxml==0.6.0

experiments/invariant-risk-minimization/requirements.txt

@@ -1,7 +1,7 @@
 appnope==0.1.0
 attrs==19.3.0
 backcall==0.1.0
-bleach==3.1.0
+bleach==3.1.1
 cycler==0.10.0
 decorator==4.4.1
 defusedxml==0.6.0