Bump babel from 2.9.0 to 2.9.1

Bumps [babel](https://github.com/python-babel/babel) from 2.9.0 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@v2.9.0...v2.9.1)

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

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

requirements.txt

@@ -4,7 +4,7 @@ appdirs==1.4.4
 asn1crypto==1.4.0
 async-timeout==3.0.1
 attrs==20.3.0
-Babel==2.9.0
+Babel==2.9.1
 backports.functools-lru-cache==1.6.1
 bcrypt==3.2.0
 beautifulsoup4==4.9.3