fix(themes): update incorrect import

Author: brandyscarney

core/src/themes/md/default.tokens.ts

@@ -1,8 +1,8 @@
 import { defaultTheme as baseDefaultTheme } from '../base/default.tokens';
 import type { DefaultTheme } from '../themes.interfaces';
 
-import { darkTheme } from './dark.tokens.js';
-import { lightTheme } from './light.tokens.js';
+import { darkTheme } from './dark.tokens';
+import { lightTheme } from './light.tokens';
 
 export const defaultTheme: DefaultTheme = {
   ...baseDefaultTheme,