[maint]: Re-add `--no-pager` option to `zinit self-update`

### Summary

See https://github.com/zdharma-continuum/zinit/pull/173#discussion_r871271255.

``` sh
cd ~/.local/share/zinit/zinit.git
git reset --hard HEAD~300
```

Then, the following commands stop until user presses `q` to quit the pager.

``` sh
zinit self-update
# or
zinit self-update -q
```

### Proposed fix

_No response_