Bump mailmanclient from 3.3.4 to 3.3.5 in /web (#587)

Bumps [mailmanclient](https://gitlab.com/mailman/mailmanclient) from 3.3.4 to 3.3.5.
- [Release notes](https://gitlab.com/mailman/mailmanclient/tags)
- [Commits](https://gitlab.com/mailman/mailmanclient/compare/3.3.4...3.3.5)

---
updated-dependencies:
- dependency-name: mailmanclient
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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web/requirements.txt

@@ -1,4 +1,4 @@
-mailmanclient==3.3.4
+mailmanclient==3.3.5
 postorius==1.3.7
 hyperkitty==1.3.7
 django-mailman3==1.3.8