fix(deps): update dependency vuepress to v2.0.0-rc.15

Author: renovate[bot]

package.json

@@ -36,7 +36,7 @@
     "three": "0.164.1",
     "vidstack": "1.11.21",
     "vue": "3.4.27",
-    "vuepress": "2.0.0-rc.9",
+    "vuepress": "2.0.0-rc.15",
     "vuepress-plugin-search-pro": "2.0.0-rc.38",
     "vuepress-shared": "2.0.0-rc.38",
     "vuepress-theme-hope": "2.0.0-rc.38"