pre_visit_relation not invoked for Drop query

Hi,

I am using the pre_visit_relation to extract tables from queries and I found that for some reason,
Drop Table t1 not invoked the pre_visit_relation method.

Do you know if this is the expected behaviour? or it will be supported in next versions?

thanks.

Reproduce the reported `Drop Table t1` case with `pre_visit_relation` and compare it with a query where the callback runs. Inspect the parser and visitor handling for DROP statements, along with any existing visitor tests; done means the expected behavior is established and covered by a regression test or documented clearly.

Written by the indexing model from the issue text.