Bump zope-interface from 6.4.post2 to 7.1.0

Bumps [zope-interface](https://github.com/zopefoundation/zope.interface) from 6.4.post2 to 7.1.0.
- [Changelog](https://github.com/zopefoundation/zope.interface/blob/master/CHANGES.rst)
- [Commits](zopefoundation/zope.interface@6.4.post2...7.1.0)

---
updated-dependencies:
- dependency-name: zope-interface
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>

requirements.txt

@@ -1,2 +1,2 @@
 zc.buildout==3.2.0
-zope.interface==6.4.post2
+zope.interface==7.1.0