Use maps.Copy for simpler map handling (#7009)

Signed-off-by: eveneast <qcqs@foxmail.com>

cmd/commandfuncs.go

@@ -24,6 +24,7 @@ import (
 	"io"
 	"io/fs"
 	"log"
+	"maps"
 	"net"
 	"net/http"
 	"os"
@@ -703,9 +704,7 @@ func AdminAPIRequest(adminAddr, method, uri string, headers http.Header, body io
 	if body != nil {
 		req.Header.Set("Content-Type", "application/json")
 	}
-	for k, v := range headers {
-		req.Header[k] = v
-	}
+	maps.Copy(req.Header, headers)
 
 	// make an HTTP client that dials our network type, since admin
 	// endpoints aren't always TCP, which is what the default transport