Fix missing import in pooling implementation.

src/fiber_orm/pool.nim

@@ -6,8 +6,8 @@
 
 import std/[db_common, logging, sequtils, strutils, sugar]
 
-from std/db_sqlite import getRow
-from std/db_postgres import getRow
+from std/db_sqlite import getRow, close
+from std/db_postgres import getRow, close
 
 import namespaced_logging
 import ./db_common as fiber_db_common