Bump httplib2 from 0.21.0 to 0.22.0

Bumps [httplib2](https://github.com/httplib2/httplib2) from 0.21.0 to 0.22.0.
- [Release notes](https://github.com/httplib2/httplib2/releases)
- [Changelog](https://github.com/httplib2/httplib2/blob/master/CHANGELOG)
- [Commits](httplib2/httplib2@v0.21.0...v0.22.0)

---
updated-dependencies:
- dependency-name: httplib2
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

requirements.txt

@@ -47,7 +47,7 @@ fonttools==4.39.2
     # via matplotlib
 html5lib==1.1
     # via xhtml2pdf
-httplib2==0.21.0
+httplib2==0.22.0
     # via plantuml
 idna==3.4
     # via requests