lint: Update code to handle lint issues

Update code to handle lint issues after golangci-lint update to v1.6.0.

Fixes: #527

Signed-off-by: Hui Zhu <teawater@hyper.sh>

Author: teawater

grpc_test.go

@@ -869,7 +869,7 @@ func TestPosixRlimitsToRlimits(t *testing.T) {
 	assert := assert.New(t)
 
 	expectedRlimits := []configs.Rlimit{
-		{unix.RLIMIT_CPU, 100, 120},
+		{int(unix.RLIMIT_CPU), 100, 120},
 		{unix.RLIMIT_FSIZE, 100, 120},
 		{unix.RLIMIT_DATA, 100, 120},
 		{unix.RLIMIT_STACK, 100, 120},