chore(log): bad sprintf syntax (#3632)

There is no Stringer on the channel struct, so using %s causes an error.
Using %v to print the default representation instead.

Co-authored-by: Nedyalko Dyakov <1547186+ndyakov@users.noreply.github.com>

Author: ccoVeille

pubsub.go

@@ -734,7 +734,7 @@ func (c *channel) initMsgChan() {
 					}
 				case <-timer.C:
 					internal.Logger.Printf(
-						ctx, "redis: %s channel is full for %s (message is dropped)",
+						ctx, "redis: %v channel is full for %s (message is dropped)",
 						c, c.chanSendTimeout)
 				}
 			default:
@@ -788,7 +788,7 @@ func (c *channel) initAllChan() {
 					}
 				case <-timer.C:
 					internal.Logger.Printf(
-						ctx, "redis: %s channel is full for %s (message is dropped)",
+						ctx, "redis: %v channel is full for %s (message is dropped)",
 						c, c.chanSendTimeout)
 				}
 			default: