Bump hupper from 1.7 to 1.8

Bumps [hupper](https://github.com/Pylons/hupper) from 1.7 to 1.8.
- [Release notes](https://github.com/Pylons/hupper/releases)
- [Changelog](https://github.com/Pylons/hupper/blob/master/CHANGES.rst)
- [Commits](Pylons/hupper@1.7...1.8)

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

requirements.txt

@@ -9,7 +9,7 @@ colorama==0.4.1
 cornice==3.5.1
 cornice-swagger==0.7.0
 dockerflow==2019.5.0
-hupper==1.7
+hupper==1.8
 idna==2.8
 iso8601==0.1.12
 jsonpatch==1.23