Protect master branch to force contributions via Pull Requests
It would be nice to protect the master from direct commits, but still having a way to merge our own PRs when no review is required (for example when updating a dataset_infos.json file, or minor bug fixes - things that happen quite often actually).
Do you know if there's a way ? you can if you're an admin of the repo This is done. Now the master branch is protected:
- [x] Require a pull request before merging: all commits must be made to a non-protected branch and submitted via a pull request
  - Required number of approvals before merging: 1 
- [x] Require linear history: prevent merge commits from being pushed
- [x] These requirements are not enforced for administrators
- [x] Additionally, the master branch is also protected against deletion and force pushes

CC: @lhoestq @julien-c @thomwolf 
In order to have a clearer Git history in the master branch, I propose to protect it so that all contributions must be done through a Pull Request and no direct commits to master are allowed.
- The Pull Request allows to give context, discuss any potential issues and improve the quality of the contribution
- The Pull Request will eventually be squashed and merged into master with a single commit that links to the Pull Request page (with all the context/discussions)

Note that we already implemented a protection in the master branch to avoid *merge* commits and ensure a linear history. This proposal goes one step further by avoiding all kind of direct commits and forcing contributions **only** through Pull Requests.

Please note that we can temporarily deactivate this protection if we need to make a direct commit, e.g. at each new version release.

The only way GitHub allows this kind or protection is by requiring a minimal number (at least one) of approvals of the Pull Request. The inconvenient is that the PR creator cannot approve their own PR: another person must approve it before it can be merged into master. To circumvent this, we could eventually disable this protection in the master branch when an urgent commit is needed (e.g. for a hotfix) and there is no other person available at that time to approve the PR.
