Revert "Give the draft updater workflow pull requests write permission"

[foolip]

Reverts #1517

[foolip]

I tested in https://github.com/foolip/web-features/actions/runs/10315510828/job/28555822160 that this fixes the problem. I guess that be specifying permissions, only the set permissions are there, and if it's omitted the default permissions apply. I think that permissions to write to the repo was the missing bit, but don't see why we should tinker with permissions at all. It was just a failed attempt to fix the problem.

[foolip]

It's alive! #1570

Thank you @tropicadri!