patch 8.2.1752: GTK GUI: cannot map alt-? with <A-?>

Problem:    GTK GUI: cannot map alt-? with <A-?>. (Ingo Karkat)
Solution:   Adjust the characters for which the shift modifier is removed.
            (closes #7016)  Make Motif and Win32 use the same function as GTK.
diff --git a/src/version.c b/src/version.c
index 90ec322..149a3ff 100644
--- a/src/version.c
+++ b/src/version.c
@@ -751,6 +751,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1752,
+/**/
     1751,
 /**/
     1750,