Bump colander from 1.7.0 to 1.8.0

Bumps [colander](https://github.com/Pylons/colander) from 1.7.0 to 1.8.0.
- [Release notes](https://github.com/Pylons/colander/releases)
- [Changelog](https://github.com/Pylons/colander/blob/master/CHANGES.rst)
- [Commits](Pylons/colander@1.7.0...1.8.0)

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

requirements.txt

@@ -2,7 +2,7 @@ bcrypt==3.1.7
 certifi==2020.6.20
 cffi==1.14.1
 chardet==3.0.4
-colander==1.7.0
+colander==1.8.0
 colorama==0.4.3
 cornice==5.0.1
 cornice-swagger==1.0.0