terminal: know about autorepeat mode

Ignore it because xterm does

src/terminal/modes.zig

@@ -189,6 +189,7 @@ const entries: []const ModeEntry = &.{
     .{ .name = "reverse_colors", .value = 5 },
     .{ .name = "origin", .value = 6 },
     .{ .name = "wraparound", .value = 7, .default = true },
+    .{ .name = "autorepeat", .value = 8 },
     .{ .name = "mouse_event_x10", .value = 9 },
     .{ .name = "cursor_blinking", .value = 12 },
     .{ .name = "cursor_visible", .value = 25, .default = true },

src/termio/Exec.zig

@@ -1746,6 +1746,12 @@ const StreamHandler = struct {
 
         // And then some modes require additional processing.
         switch (mode) {
+            // Just noting here that autorepeat has no effect on
+            // the terminal. xterm ignores this mode and so do we.
+            // We know about just so that we don't log that it is
+            // an unknown mode.
+            .autorepeat => {},
+
             // Schedule a render since we changed colors
             .reverse_colors => try self.queueRender(),