Possible unsafe migrations warning

I'm working through the book and I see that when a migration is generated for new index it's not applying `concurrently: true`
```
def up do
create unique_index(:albums, [:name, :artist_id],
name: "albums_unique_album_names_per_artist_index"
)
end
```
This locks the table and with bigger databases can cause problems:
[postgres docs](https://www.postgresql.org/docs/current/sql-createindex.html#SQL-CREATEINDEX-CONCURRENTLY)
there are some libraries that will let you know about unsafe migrations where you can check what to avoid
[rails](https://github.com/ankane/strong_migrations?tab=readme-ov-file#adding-an-index-non-concurrently) - there is also one for [elixir](https://hexdocs.pm/excellent_migrations/readme.html) but as ash generates the migrations most of the stuff can be applied by changing the codegen.