Update bedrock-server to v15

Author: tiny-ben-tran

package.json

@@ -30,7 +30,7 @@
     "@babel/core": "^7.21.3",
     "@ephox/agar": "^7.4.1",
     "@ephox/bedrock-client": "^15.0.0",
-    "@ephox/bedrock-server": "^13.3.0",
+    "@ephox/bedrock-server": "^15.0.2",
     "@ephox/katamari": "^9.1.5",
     "@ephox/mcagar": "^8.3.2",
     "@ephox/sand": "^6.0.9",