correctly visualise all the DB versions (not just the defaults)

[alessandroargentieri]

Before the change only defaults

 $ civo database versions --region=lon1
+------------+---------+
| Name       | version |
+------------+---------+
| MySQL      |     8.0 |
+------------+---------+
| PostgreSQL |      14 |
+------------+---------+

after the change all the versions are shown:

$ civo database versions --region=lon1
+------------+---------+---------+
| Name       | Version | Default |
+------------+---------+---------+
| MySQL      |     8.0 | true    |
+------------+---------+---------+
| MySQL      |     8.4 | false   |
+------------+---------+---------+
| PostgreSQL |      14 | true    |
+------------+---------+---------+
| PostgreSQL |      15 | false   |
+------------+---------+---------+
| PostgreSQL |      16 | false   |
+------------+---------+---------+

| PostgreSQL | 17 | false |
+------------+---------+---------+