Bump babel from 2.8.0 to 2.9.1

Bumps [babel](https://github.com/python-babel/babel) from 2.8.0 to 2.9.1.
- [Release notes](https://github.com/python-babel/babel/releases)
- [Changelog](https://github.com/python-babel/babel/blob/master/CHANGES)
- [Commits](python-babel/babel@v2.8.0...v2.9.1)

---
updated-dependencies:
- dependency-name: babel
  dependency-type: direct:production
...

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

requirements.txt

@@ -5,7 +5,7 @@ astroid==2.3.3
 atomicwrites==1.4.0
 attrs==19.3.0
 autopep8 @ file:///tmp/build/80754af9/autopep8_1592412889138/work
-Babel==2.8.0
+Babel==2.9.1
 backcall==0.2.0
 bcrypt==3.1.7
 bleach==3.3.0