Store repo in pool options (#361)

Useful as options are emitted in DBConnection's telemetry events.
This change allows one to correlate these telemetry events with the pool owner repo.

Author: v0idpwn

lib/ecto/adapters/sql.ex

@@ -581,7 +581,7 @@ defmodule Ecto.Adapters.SQL do
   end
 
   @pool_opts [:timeout, :pool, :pool_size] ++
-               [:queue_target, :queue_interval, :ownership_timeout]
+               [:queue_target, :queue_interval, :ownership_timeout, :repo]
 
   @doc false
   def init(connection, driver, config) do