Use SplitSeq for CAA issuer domain labels

go fix on Go 1.26 rewrites strings.Split range loops to
SplitSeq; apply that so lint-go passes.

Signed-off-by: Cursor Agent <cursoragent@cursor.com>

Co-authored-by: Bryan FRIMIN <bryan@frimin.fr>

pkg/dnsclient/caa.go

@@ -233,8 +233,8 @@ func isCAAIssuerDomainName(name string) bool {
 		return false
 	}
 
-	labels := strings.Split(name, ".")
-	for _, label := range labels {
+	labels := strings.SplitSeq(name, ".")
+	for label := range labels {
 		if !isCAAIssuerLabel(label) {
 			return false
 		}