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>

Author: dependabot[bot]

Pipfile

@@ -18,7 +18,7 @@ cssselect2 = "==0.3.0"
 decorator = "==4.4.2"
 defusedxml = "==0.6.0"
 future = "==0.18.2"
-httplib2 = "==0.18.0"
+httplib2 = "==0.19.0"
 idna = "==2.9"
 instagram = {git = "https://github.com/foozmeat/python-instagram.git"}
 itsdangerous = "==1.1.0"