fix(deps): update dependency yjs to ^13.6.15

Author: renovate[bot]

package-lock.json

@@ -111,7 +111,7 @@
     "y-prosemirror": "^1.0.20",
     "y-protocols": "^1.0.6",
     "y-websocket": "^2.0.2",
-    "yjs": "^13.6.14"
+    "yjs": "^13.6.15"
   },
   "engines": {
     "node": "^20.0.0",