Bump babel from 2.8.0 to 2.9.1 (#35)

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](https://github.com/python-babel/babel/compare/v2.8.0...v2.9.1)

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

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

requirement_files/Sphinx.txt

@@ -1,5 +1,5 @@
 alabaster==0.7.12
-Babel==2.8.0
+Babel==2.9.1
 certifi==2020.6.20
 chardet==3.0.4
 docutils==0.16

requirements_opinionated.txt

@@ -6,7 +6,7 @@ asn1crypto==1.4.0
 aspy.yaml==1.3.0
 atomicwrites==1.4.0
 attrs==19.3.0
-Babel==2.8.0
+Babel==2.9.1
 black==19.10b0
 boto==2.49.0
 certifi==2020.6.20