fix: shim theme name for shiki

[nekowinston]

Without this fix, Shiki (at least in Astro) would generate wrong class names:

This could be fixed via

import { mocha } from "@catppuccin/vscode";
import { defineConfig } from "astro/config";

export default defineConfig({
  markdown: {
    shikiConfig: {
      theme: {
        ...mocha,
        name: "catppuccin-mocha",
      },
    },
  },
});

but it makes sense to shim this for the library user.