fix: ensure we only use default vue 3.x build in vitest

We’ll only use vitest for non-compat Vue 3 code. But application code
may still rely on @vue/compat (as specified in the vite config).

If we don’t specify the exact vue package for tests, we’ll run into this
error: https://github.com/vuejs/core/issues/4344.

vitest.config.ts

@@ -6,5 +6,10 @@ const vitestConfig = defineConfig({
     environment: 'happy-dom',
     include: ['src/**/*.{test,spec}.ts', 'vitest/**/*.{test,spec}.ts'],
   },
+  resolve: {
+    alias: {
+      vue: 'vue',
+    },
+  },
 })
 export default mergeConfig(viteConfig, vitestConfig)