feat: make Grafana provision dashboard and datasource automatically in docker compose

[iTrooz]

What does this PR change? What problem does it solve?

The docker compose setup wasn't working (probably out of date ?) and provisioning wasn't done automatically

Was the change previously discussed in an issue or on the forum?

Checklist

• [ ] I have added tests for all code changes.
• [ ] I have added documentation for relevant changes (in the manual).
• [x] There's a new file in changelog/unreleased/ that describes the changes for our users (see template).
• [x] I'm done! This pull request is ready for review.

[iTrooz]

Btw, your pull request template says - Format all commit messages in the same style as [the other commits in the repository](https://github.com/restic/rest-server/blob/master/CONTRIBUTING.md#git-commits). but there is no such file on the repository ):