[gnome-control-center] printers: Fix missing const on string parameter

[Robert Ancell <rancell src gnome org>]

commit f9fd2587ca0ba2b766ee159394ab0dd65dbc335a
Author: Robert Ancell <robert ancell canonical com>
Date:   Wed May 11 12:09:25 2022 +1200

    printers: Fix missing const on string parameter

 panels/printers/pp-utils.c | 2 +-
 panels/printers/pp-utils.h | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/panels/printers/pp-utils.c b/panels/printers/pp-utils.c
index 4cd22e3f4..750b634c6 100644
--- a/panels/printers/pp-utils.c
+++ b/panels/printers/pp-utils.c
@@ -3638,7 +3638,7 @@ shift_string_left (gchar *str)
 }
 
 gboolean
-printer_name_is_valid (gchar *str)
+printer_name_is_valid (const gchar *str)
 {
   const gchar *invalid_chars = " \t#/";
   return strlen(str) == strcspn(str, invalid_chars);
diff --git a/panels/printers/pp-utils.h b/panels/printers/pp-utils.h
index 50c48c0cf..332cda4e7 100644
--- a/panels/printers/pp-utils.h
+++ b/panels/printers/pp-utils.h
@@ -258,6 +258,6 @@ gchar      *canonicalize_device_name (GList         *device_names,
 
 void        shift_string_left (gchar *str);
 
-gboolean    printer_name_is_valid (gchar *str);
+gboolean    printer_name_is_valid (const gchar *str);
 
 G_END_DECLS