Allow to set Catalan localization

[malcp]

Problem/Motivation

One cannot configure Grocy to use the Catalan localization.

Expected behavior

It is possible to configure Grocy with "culture: ca".

Actual behavior

It is not possible to configure Grocy with "culture: ca". The UI shows the following error when atemting to save:

value must be one of ['cs', 'da', 'de', 'el_GR', 'en', 'en_GB', 'es', 'fi', 'fr', 'he_IL', 'hu', 'it', 'ja', 'ko_KR', 'nl', 'no', 'pl', 'pt_BR', 'pt_PT', 'ru', 'sk_SK', 'sv_SE', 'ta', 'tr', 'zh_CN', 'zh_TW'].

Steps to reproduce

1. Install the addon.
2. Try to configure it with "culture: ca".

Proposed changes

Add "ca" in the cultures list in grocy/config.yaml.

[malcp]

This depends on Grocy version >= 3.2.0. So, it's probably more reasonable to include this change in #280