Bump httpretty from 0.9.7 to 1.1.3

Bumps [httpretty](https://github.com/gabrielfalcao/HTTPretty) from 0.9.7 to 1.1.3.
- [Release notes](https://github.com/gabrielfalcao/HTTPretty/releases)
- [Changelog](https://github.com/gabrielfalcao/HTTPretty/blob/master/.release)
- [Commits](https://github.com/gabrielfalcao/HTTPretty/compare/0.9.7...1.1.3)

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

requirements.txt

@@ -4,7 +4,7 @@ feedparser==5.2.1
 GitPython
 google-cloud-datastore==1.10.0
 html-similarity==0.3.2
-httpretty==0.9.7
+httpretty==1.1.3
 pyopenssl==18.0.0
 PyYAML
 requests==2.22.0