Remove duplicate plugins that already included in default theme

Author: hustcer

package-lock.json

@@ -15,12 +15,8 @@
   "license": "MIT",
   "devDependencies": {
     "@vuepress/bundler-vite": "2.0.0-rc.26",
-    "@vuepress/plugin-back-to-top": "2.0.0-rc.118",
-    "@vuepress/plugin-copy-code": "2.0.0-rc.118",
     "@vuepress/plugin-docsearch": "2.0.0-rc.118",
     "@vuepress/plugin-feed": "2.0.0-rc.118",
-    "@vuepress/plugin-git": "2.0.0-rc.118",
-    "@vuepress/plugin-medium-zoom": "2.0.0-rc.118",
     "@vuepress/plugin-shiki": "2.0.0-rc.118",
     "@vuepress/plugin-sitemap": "2.0.0-rc.118",
     "@vuepress/theme-default": "2.0.0-rc.118",