[exporter/syslogexporter] run make modernize (open-telemetry#43189)

<!--Ex. Fixing a bug - Describe the bug and how this fixes the issue.
Ex. Adding a feature - Explain what this achieves.-->
#### Description

Run `make modernize` on `syslogexporter`

Signed-off-by: Paulo Dias <[email protected]>

Author: paulojmdias

receiver/syslogreceiver/syslog_test.go

@@ -54,7 +54,7 @@ func testSyslog(t *testing.T, cfg *SysLogConfig) {
 		require.NoError(t, err)
 	}
 
-	for i := 0; i < numLogs; i++ {
+	for i := range numLogs {
 		msg := fmt.Sprintf("<86>1 2021-02-28T00:0%d:02.003Z 192.168.1.1 SecureAuth0 23108 ID52020 [SecureAuth@27389] test msg %d\n", i, i)
 		_, err = conn.Write([]byte(msg))
 		require.NoError(t, err)
@@ -68,7 +68,7 @@ func testSyslog(t *testing.T, cfg *SysLogConfig) {
 	resourceLogs := sink.AllLogs()[0].ResourceLogs().At(0)
 	logs := resourceLogs.ScopeLogs().At(0).LogRecords()
 
-	for i := 0; i < numLogs; i++ {
+	for i := range numLogs {
 		log := logs.At(i)
 
 		require.Equal(t, log.Timestamp(), pcommon.Timestamp(1614470402003000000+i*60*1000*1000*1000))