fix(examples): sync exactly_once and consumergroup

- ensure both examples handle sarama.ErrClosedConsumerGroup in the
  Consume for { ... } loop and ignore that error as it means the user
  has closed the ConsumerGroup directly via Close().
- ensure exactly_once handles the Messages() channel being closed with
  an ok check.
- copy assignment strategy optional flag from consumergroup into
  exactly_once sample
- bump the go.mod of both to specify 1.40.1 by default (although we
  still replace to ../.. anyway)

Signed-off-by: Dominic Evans <dominic.evans@uk.ibm.com>

examples/consumergroup/go.mod

@@ -2,6 +2,6 @@ module github.com/IBM/sarama/examples/consumer
 
 go 1.16
 
-require github.com/IBM/sarama v1.34.1
+require github.com/IBM/sarama v1.40.1
 
 replace github.com/IBM/sarama => ../../

examples/consumergroup/main.go

@@ -3,6 +3,7 @@ package main
 // SIGUSR1 toggle the pause/resume consumption
 import (
 	"context"
+	"errors"
 	"flag"
 	"log"
 	"os"
@@ -106,6 +107,9 @@ func main() {
 			// server-side rebalance happens, the consumer session will need to be
 			// recreated to get the new claims
 			if err := client.Consume(ctx, strings.Split(topics, ","), &consumer); err != nil {
+				if errors.Is(err, sarama.ErrClosedConsumerGroup) {
+					return
+				}
 				log.Panicf("Error from consumer: %v", err)
 			}
 			// check if context was cancelled, signaling that the consumer should stop

examples/exactly_once/go.mod

@@ -2,6 +2,6 @@ module github.com/IBM/sarama/examples/exactly_once
 
 go 1.16
 
-require github.com/IBM/sarama v1.34.1
+require github.com/IBM/sarama v1.40.1
 
 replace github.com/IBM/sarama => ../../