sq inspect metadata doesn't populate the "schema" field for MySQL, SQLite, or SQL Server.

[neilotoole]

sq inspect returns schema for Postgres, but is empty/omitted for other drivers.

$ sq inspect @sakila_pg12 -j
{
  "handle": "@sakila_pg12",
  "location": "postgres://sakila:xxxxx@192.168.50.132/sakila",
  "name": "sakila",
  "name_fq": "sakila.public",
  "schema": "public",
  "driver": "postgres",

[neilotoole]

Fixed.