REF: FD001

Is your feature request related to a problem? Please describe.
We're saving all the Meetings Inscription data forever. For privacy and legal reasons (GDPR) we shouldn't do that.

Describe the solution you'd like
We should have a rake task (that gets executed on a crontab) for deleting this personal data. It should remove all the data of the Inscriptios table 3 months after the end date of the meeting.

Describe alternatives you've considered
To have other way of doing this (like whenever gem), but at the moment on Decidim we're working with cron.

Additional context
Principle of Data Minimization on GDPR

Does this issue could impact on users private data?
Yes, it's actually about removing this data

Acceptance criteria

• As a Decidim implementer I can create a crontab that deletes inscription data 3 months after the end date of the meeting
• I have the crontab configuration on documentation