Bump zope-interface from 4.6.0 to 4.7.1

Bumps [zope-interface](https://github.com/zopefoundation/zope.interface) from 4.6.0 to 4.7.1.
- [Release notes](https://github.com/zopefoundation/zope.interface/releases)
- [Changelog](https://github.com/zopefoundation/zope.interface/blob/master/CHANGES.rst)
- [Commits](zopefoundation/zope.interface@4.6.0...4.7.1)

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

requirements.txt

@@ -35,4 +35,4 @@ venusian==3.0.0
 waitress==1.3.1
 WebOb==1.8.5
 zope.deprecation==4.4.0
-zope.interface==4.6.0
+zope.interface==4.7.1