Bump httplib2 from 0.18.0 to 0.19.0

Bumps [httplib2](https://github.com/httplib2/httplib2) from 0.18.0 to 0.19.0.
- [Release notes](https://github.com/httplib2/httplib2/releases)
- [Changelog](https://github.com/httplib2/httplib2/blob/master/CHANGELOG)
- [Commits](httplib2/httplib2@v0.18.0...v0.19.0)

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

requirements.txt

@@ -10,7 +10,7 @@ google-auth==1.11.3
 google-auth-httplib2==0.0.3
 google-auth-oauthlib==0.4.1
 googleapis-common-protos==1.51.0
-httplib2==0.18.0
+httplib2==0.19.0
 idna==2.9
 jdcal==1.4.1
 oauthlib==3.1.0