Switch to "colorSchemes" from "palette" API in mui theme

"colorSchemes" is the preferred api starting from mui v6

src/lib/mui/MuiStyles.types.d.ts

@@ -0,0 +1,15 @@
+/*
+ * Copyright (C) Contributors to the Suwayomi project
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/.
+ */
+
+import '@mui/material/styles';
+
+declare module '@mui/material/styles' {
+    interface CssThemeVariables {
+        enabled: true;
+    }
+}