Bump zope-event from 5.1 to 6.0 (#1555)

Bumps [zope-event](https://github.com/zopefoundation/zope.event) from 5.1 to 6.0.
- [Changelog](https://github.com/zopefoundation/zope.event/blob/master/CHANGES.rst)
- [Commits](zopefoundation/zope.event@5.1...6.0)

---
updated-dependencies:
- dependency-name: zope-event
  dependency-version: '6.0'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

constraints.txt

@@ -43,5 +43,5 @@ tornado==4.5.3
 typing_extensions==4.14.0
 urllib3==2.5.0
 Werkzeug==0.16.1
-zope.event==5.1
+zope.event==6.0
 zope.interface==7.2