Bump cornice from 4.0.1 to 5.0.0

Bumps [cornice](https://github.com/mozilla-services/cornice) from 4.0.1 to 5.0.0.
- [Release notes](https://github.com/mozilla-services/cornice/releases)
- [Changelog](https://github.com/Cornices/cornice/blob/master/CHANGES.txt)
- [Commits](Cornices/cornice@4.0.1...5.0.0)

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

requirements.txt

@@ -6,7 +6,7 @@ cffi==1.14.0
 chardet==3.0.4
 colander==1.7.0
 colorama==0.4.3
-cornice==4.0.1
+cornice==5.0.0
 cornice-swagger==1.0.0
 cryptography==2.9.2
 dockerflow==2019.10.0