a11y: Map GTK terminal role to AT-SPI

AT-SPI has a terminal role for virtual terminals.

Fixes: #6462

gtk/a11y/gtkatspiutils.c

@@ -291,6 +291,9 @@ gtk_accessible_role_to_atspi_role (GtkAccessibleRole role)
     case GTK_ACCESSIBLE_ROLE_TOGGLE_BUTTON:
       return ATSPI_ROLE_TOGGLE_BUTTON;
 
+    case GTK_ACCESSIBLE_ROLE_TERMINAL:
+      return ATSPI_ROLE_TERMINAL;
+
     default:
       break;
     }