Note that this release includes a fix for Github security advisory
`GHSA-g936-w68m-87j8 <https://github.com/open-formulieren/open-forms/security/advisories/GHSA-g936-w68m-87j8>`_.

* Upgraded to latest Django security release
* [#1730] Update allowed headers for nonce CSP header
* [#1325] Added management command to check number of forms with duplicate component
  keys (required for upgrade to 1.2 when it's available)
* [#1723] StUF-ZDS registration: a number of configuration options are now optional
* [#1769] StUF-ZDS registration: you can now configure the confidentiality level of a
  document attached to the zaak
* [#1617] Fixed crash on StUF onvolledige datum
* [GHSA-g936-w68m-87j8] Perform additional permission checks if the form requires
  login
* Backported Submission.is_authenticated from #1418