Bump httplib2 from 0.14.0 to 0.19.0

Bumps [httplib2](https://github.com/httplib2/httplib2) from 0.14.0 to 0.19.0.
- [Release notes](https://github.com/httplib2/httplib2/releases)
- [Changelog](https://github.com/httplib2/httplib2/blob/master/CHANGELOG)
- [Commits](httplib2/httplib2@v0.14.0...v0.19.0)

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

Author: dependabot[bot]

requirements.txt

@@ -13,7 +13,7 @@ google-cloud-storage==1.23.0
 google-resumable-media==0.5.0
 googleapis-common-protos==1.6.0
 grpcio==1.25.0
-httplib2==0.14.0
+httplib2==0.19.0
 idna==2.8
 msgpack==0.6.2
 Pillow==8.3.2