ci: rebase before pushing release/pre-release commits (#1109)

## Summary
Add `pull: '--rebase --autostash'` to the `EndBug/add-and-commit` step
in the `update_changelog` jobs of both `release.yaml` and
`pre_release.yaml`, so the changelog/version commits survive a
concurrent ref update on master.

## Context
Same race that bit `apify/apify-client-js` in [run
25114327598](https://github.com/apify/apify-client-js/actions/runs/25114327598/job/73597522121):

```
remote rejected (cannot lock ref 'refs/heads/master': is at <new> but expected <old>)
```

The bypass logs `remote: Bypassed rule violations for refs/heads/master`
— so it's not permissions, it's just non-fast-forward because something
landed on master between checkout and push. `pre_release.yaml` is
especially exposed since it's triggered on every push to master.

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