bump version

Signed-off-by: ryjiang <jiangruiyi@gmail.com>

server/package.json

@@ -1,6 +1,6 @@
 {
   "name": "attu",
-  "version": "2.5.5",
+  "version": "2.5.6",
   "license": "MIT",
   "author": {
     "name": "zilliz",