Update jupyterhub-ldapauthenticator requirement in /images/hub/unfrozen

Updates the requirements on [jupyterhub-ldapauthenticator](https://github.com/jupyterhub/ldapauthenticator) to permit the latest version.
- [Release notes](https://github.com/jupyterhub/ldapauthenticator/releases)
- [Changelog](https://github.com/jupyterhub/ldapauthenticator/blob/main/CHANGELOG.md)
- [Commits](jupyterhub/ldapauthenticator@v1.0...2.0.1)

---
updated-dependencies:
- dependency-name: jupyterhub-ldapauthenticator
  dependency-type: direct:production
...

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

images/hub/unfrozen/requirements.txt

@@ -16,7 +16,7 @@ jupyterhub-kubespawner==6.*
 # JupyterHub Authenticator choices
 jupyterhub-firstuseauthenticator==1.*
 jupyterhub-hmacauthenticator==1.*
-jupyterhub-ldapauthenticator==1.*
+jupyterhub-ldapauthenticator==2.*
 jupyterhub-ltiauthenticator==1.*
 jupyterhub-nativeauthenticator==1.*
 jupyterhub-tmpauthenticator==1.*