Fix parallel fetching of the vaccin times

[PierreMesure]

Problem

I implemented my scripts so I could split fetching the times by region. The goal was to run them in parallel.

However, that trigger race conditions when it comes to pushing the data on Github. I tried to activate autorebase and autostash but it seems like there are still too many pushes at the same time and it triggers an error in some cases.

Suggested solution

• Implement a simple pull and retry after a few seconds if the push fails?
• Make the processes aware of each other in any way? I'm not sure how that could work, I'm no Github Actions pro.

[PierreMesure]

This is almost completely implemented but I haven't activated it yet to avoid putting a more intense burden on the infrastructure of MittVaccin.