Release 2.9

It is that time of the year again.

See [CHANGELOG.md](https://gitlab.federez.net/re2o/re2o/-/blob/release-2.9/CHANGELOG.md).

Many thanks to the people who made Re2o2.9 possible, thanks to their 575 commits in almost one year of development!

* Jean-Romain Garnier
* Gabriel Detraz
* Hugo Levy-Falk
* Arthur Grisel-Davy
* Corentin Canebier
* Yoann Piétri
* Jean-Marie Mineau
* Leila Bekaddour
* Maxime Bombar

See merge request re2o/re2o!592

Replace date_end by date_end_memb in voucher_pdf. Close #315

See the issue for details.

Closes #317 .

The Entire LDAP infrastructures now relies on signals rather than direct function calls and is in its own app. This means it can be deactivated, but also that we can easily plug new services in addition to LDAP, such as OAuth.

Closes issue #270

We made it this far folks.

Closes #307


Co-authored-by: Jean-Romain Garnier <jean-romain.garnier@supelec.fr>
Co-authored-by: Hugo Levy-Falk <hugo@klafyvel.me>