feat: enable unparam lint

Signed-off-by: Wei Fu <fuweid89@gmail.com>

tests/integration/clientv3/concurrency/example_stm_test.go

@@ -50,11 +50,11 @@ func ExampleSTM_apply() {
 				}
 			}
 
-			exchange := func(stm concurrency.STM) error {
+			exchange := func(stm concurrency.STM) {
 				from, to := rand.Intn(totalAccounts), rand.Intn(totalAccounts)
 				if from == to {
 					// nothing to do
-					return nil
+					return
 				}
 				// read values
 				fromK, toK := fmt.Sprintf("accts/%d", from), fmt.Sprintf("accts/%d", to)
@@ -70,7 +70,7 @@ func ExampleSTM_apply() {
 				// write back
 				stm.Put(fromK, fmt.Sprintf("%d", fromInt))
 				stm.Put(toK, fmt.Sprintf("%d", toInt))
-				return nil
+				return
 			}
 
 			// concurrently exchange values between accounts
@@ -79,7 +79,10 @@ func ExampleSTM_apply() {
 			for i := 0; i < 10; i++ {
 				go func() {
 					defer wg.Done()
-					if _, serr := concurrency.NewSTM(cli, exchange); serr != nil {
+					if _, serr := concurrency.NewSTM(cli, func(stm concurrency.STM) error {
+						exchange(stm)
+						return nil
+					}); serr != nil {
 						log.Fatal(serr)
 					}
 				}()