Restore harlequin-databricks as optional dep

I think the deps issues on locking could have come
from upper bounds on the pyarrow & numpy version
set by the databricks-sql-connector

Those upper bounds have gone in the latest
databricks-sql-connector release (3.7.0), which is a
requirement of the latest harlequin-databricks release
(0.5.2)

databricks/databricks-sql-python#452

pyproject.toml

@@ -59,7 +59,7 @@ harlequin-mysql = { version = ">=0.1", optional = true }
 harlequin-odbc = { version = ">=0.1", optional = true }
 harlequin-bigquery = { version = "^1.0", optional = true }
 harlequin-trino = { version = ">=0.1", optional = true }
-# harlequin-databricks = { version = ">=0.3", optional = true }
+harlequin-databricks = { version = ">=0.5.2", optional = true }
 harlequin-adbc = { version = ">=0.1", optional = true }
 harlequin-cassandra = { version = ">=0.1", optional = true }
 harlequin-nebulagraph = { version = ">=0.1", optional = true }