rofi(config): use alt+meta for keybindings custom

From this issue:
davatorium/rofi#2095

Seems like there's some changes with `xkbcommon` which cause `alt`
keybinding to not working as expected. So remap the `kb-custom` to
`alt-meta` instead of only `alt` and see how it goes.

.config/rofi/config.rasi

@@ -9,6 +9,17 @@ configuration {
 	display-drun: "_";
 	display-combi: "exe";
 	cycle: false;
+
+	kb-custom-1: "Alt+Meta+1";
+	kb-custom-2: "Alt+Meta+2";
+	kb-custom-3: "Alt+Meta+3";
+	kb-custom-4: "Alt+Meta+4";
+	kb-custom-5: "Alt+Meta+5";
+	kb-custom-6: "Alt+Meta+6";
+	kb-custom-7: "Alt+Meta+7";
+	kb-custom-8: "Alt+Meta+8";
+	kb-custom-9: "Alt+Meta+9";
+	kb-custom-10: "Alt+Meta+0";
 }
 
 @theme "~/.config/rofi/themes/insanity.rasi"