VCF file for member list

[Furkan Şimşekli]

@ikolomiko used to use a script to add new members back in the days.

https://github.com/ikolomiko/csv2vcf can be ported here. Additionally, a record of previously added members should be stored somewhere.

https://docs.djangoproject.com/en/5.0/ref/contrib/admin/actions/#adding-actions-to-the-modeladmin