fix(vue)!: drop Vue 2 support (#439)

* fix!: drop Vue 2 support

* chore: missed

* chore: useless test

* chore: sync lock

* chore: conflicts

* doc: update for Vue 2

Author: harlan-zw

docs/content/1.setup/4.vue/0.installation.md

@@ -5,6 +5,10 @@ navigation:
   title: 'Installation'
 ---
 
+## Introduction
+
+Unhead is the official head management library for Vue. It provides a simple and intuitive API for managing the head of your application, including the title, meta tags, and other elements that are important for SEO and user experience.
+
 ## Setup
 
 1. Install `@unhead/vue` dependency to your project:
@@ -25,14 +29,31 @@ pnpm add @unhead/vue
 
 ::
 
+If you're using Vue 2, you will need to install v1 of `@unhead/vue` instead.
+
+::code-group
+
+```bash [yarn]
+yarn add @unhead/vue@^1
+```
+
+```bash [npm]
+npm install @unhead/vue@^1
+```
+
+```bash [pnpm]
+pnpm add @unhead/vue@^1
+```
+
+::
+
+
 ### Demos
 
 - [StackBlitz - Vite - Vue SPA](https://stackblitz.com/edit/vitejs-vite-uijgqa?file=package.json)
 
 2. Register the Vue plugin:
 
-::code-group
-
 ```ts [Vue 3]
 import { createHead } from '@unhead/vue'
 import { createApp } from 'vue'
@@ -46,6 +67,7 @@ app.mount('#app')
 ```
 
 ```ts [Vue 2]
+// You must use v1 of Unhead for Vue 2 support
 import { createHead } from '@unhead/vue'
 import { UnheadPlugin } from '@unhead/vue/vue2'
 import Vue from 'vue'