Support building with Go 1.20 (#3)

* Support building with Go 1.20

* Remove use of features requiring Go 1.22

Author: dgolub-huntress

go.mod

@@ -1,5 +1,5 @@
 module github.com/huntresslabs/go-systemd
 
-go 1.23
+go 1.20
 
 require github.com/godbus/dbus/v5 v5.1.0

import1/dbus_test.go

@@ -36,7 +36,7 @@ func cleanupImport(t *testing.T, name string) {
 			err error
 			dur = 500 * time.Millisecond
 		)
-		for range 5 {
+		for i := 0; i < 5; i++ {
 			time.Sleep(dur)
 			out, err = exec.Command("machinectl", "remove", name).CombinedOutput()
 			if err == nil {

internal/dlopen/dlopen_test.go

@@ -88,7 +88,7 @@ func TestDlopenThreadSafety(t *testing.T) {
 	wg := sync.WaitGroup{}
 	wg.Add(count)
 
-	for range count {
+	for i := 0; i < count; i++ {
 		go func() {
 			defer wg.Done()
 			lib, err := GetHandle(libs)

sdjournal/journal_test.go

@@ -406,7 +406,7 @@ func TestJournalGetCatalog(t *testing.T) {
 
 	// Look for an entry with MESSAGE_ID (required for GetCatalog).
 	found := false
-	for range 100 {
+	for i := 0; i < 100; i++ {
 		n, err := j.Next()
 		if err != nil {
 			t.Fatalf("Error reading journal: %s", err)

unit/option.go

@@ -49,7 +49,7 @@ func AllMatch(u1 []*UnitOption, u2 []*UnitOption) bool {
 		return false
 	}
 
-	for i := range length {
+	for i := 0; i < length; i++ {
 		if !u1[i].Match(u2[i]) {
 			return false
 		}