Clean up company data attributes and uniformize them

[4www]

Currently the data in this repo, for companies, has issues, for examples with dates.

That leads to having the sqlite3 database tables to be generated with for example dates (created_at and updated_at) in different formats (cleanup here, in post processing https://gitlab.com/joblist/workers/-/merge_requests/2).

We should fix the data in two places:

• in the cms, to be sure that the data is created by the CMS (and user), in the correct format https://gitlab.com/joblist/cms
• in the data repo, to cleanup existing data in the correct format (sent also by the CMS)