### Godot version

v4.0.beta15.official [4fa6edc88]

### System information

Windows 10

### Issue description

I use a custom keyboard layout (I made it myself), and it has «dead keys» (just like International keyboard layouts have). For example, if I press `'`, nothing happens, but if I press `a` after that, I'll get `á`. If I press `'` and `Space`, I'll get just `'`. And with my layout:
If I press `Shift + .` and then `a`, I will get `ᵄ`.
If I press `Shift + .` and then `Space`, I will get `>`.
If I press `Shift + [` and then `5`, I will get `₅`.
If I press `Shift + [` and then `Space`, I will get `{`.
In beta 14 and before, everything worked fine, but in beta 15 when I press `Shift + .` and `Space`, just nothing happens, I don't get `>`. Same for `Shift + [` and `Space`, I don't get `>`. It seems the problem is with `Shift`, because I still can type `á` (`'` and `a`) or `'` (`'` and `Space`), but not `ä` (`Shift + '` and `a`) or `"` (`Shift + '` and `Space`). In the latter cases I get `á` and `'` as if `Shift` were never pressed.

### Steps to reproduce

Install/add US International keyboard layout or [Extended Latin keyboard layout](https://github.com/godotengine/godot/files/10494466/Layouts.zip) (just run `Extended Latin\ExtLat6\setup.exe`).
Open script editor.
Press `Shift + '`.
Then press `a`.

### Minimal reproduction project

N/A
mm.instantiate();
			mm->set_window_id(receiving_window_id);
			mm->set_ctrl_pressed((wParam & MK_CONTROL) != 0);
			mm->set_shift_pressed((wParam & MK_SHIFT) != 0);
			mm->set_alt_pressed(alt_mem);
			if ((tablet_get_current_driver() == "wintab") && wintab_available && windows[window_id].wtctx) {
				
				if (windows[window_id].last_pressure_update < 10) {
					windows[window_id].last_pressure_update++;
				} else {
					windows[window_id].last_tilt = Vector2();
					windows[window_id].last_pressure = (wParam & MK_LBUTTON) ? 1.0f : 0.0f;
					windows[window_id].last_pen_inverted = false;
				}
			} else {
				windows[window_id].last_tilt = Vector2();
				windows[window_id].last_pressure = (wParam & MK_LBUTTON) ? 1.0f : 0.0f;
				windows[window_id].last_pen_inverted = false;
			}
			mm->set_pressure(windows[window_id].last_pressure);
			mm->set_tilt(windows[window_id].last_tilt);
			mm->set_pen_inverted(windows[window_id].last_pen_inverted);
			mm->set_button_mask(last_button_state);
			mm->set_position(Vector2(GET_X_LPARAM(lParam), GET_Y_LPARAM(lParam)));
			mm->set_global_position(Vector2(GET_X_LPARAM(lParam), GET_Y_LPARAM(lParam)));
			if (mouse_mode == MOUSE_MODE_CAPTURED) {
				Point2i c(windows[window_id].width / 2, windows[window_id].height / 2);
				old_x = c.x;
				old_y = c.y;
				if (mm->get_position() == c) {