Wrong permissions on volumes

Hey!
There are problem with permissions in kamal. I've added volume

```yaml
ssh:
user: alec

####################

volumes:
- ./storage:/rails/public/uploads:rw
```

in my `deploy.yml` file and got a problem with permissions:

As you see - I've configured kamal to use user `alec`, but volume was created by/for `root`. It cause problems like this:

Start with the volume configuration shown in deploy.yml and trace how Kamal creates and mounts that volume when ssh.user is set to alec. Reproduce the deployment and verify that the mounted path is usable by alec rather than owned only by root.

Written by the indexing model from the issue text.