API changes

library switched to non-consuming API:

// pre 0.24.0:
let conn = conn.query_drop("DO 1").await?;

// 0.24.0:
conn.query_drop("DO 1").await?;

Queryable trait was updated and now it is more convenient to work with usual single-result sets.
Use Queryable::query_iter and Queryable::exec_iter if you need more flexibility.
Query trait was introduced. It allows you to run queries directly on a Pool and to create 'static QueryResults
Thick Stmt structure was removed in favor of the Statement structure, which is a thin wrapper over raw statement identifier and metadata.

Fixes