Turns out the default timeout for github actions is 6 hours (!). This PR
sets some reasonable default for all workflows, the ones invoking cargo
in some way are limited to 60 minutes and the remaining ones to
10-15mins.
## What
Fail all PRs that are opened from the master/main branch of the fork.
## Why
PR:s opened from the `master` branch cannot be collaborated on. That is,
we maintainers cannot push our own commits to it (e.g. to fix smaller
problems with it before merging).
## How
Untested code straight from Claude 3.7 😅
