Fix build break with fmt 10.1.1 in mcstat.cc

Change-Id: I22b00c968fe7af9f6d0ceea3f8c82e6c6159fad2
Reviewed-on: https://review.couchbase.org/c/kv_engine/+/203425
Tested-by: Trond Norbye <[email protected]>
Reviewed-by: Paolo Cocchi <[email protected]>

Author: trondn

programs/mcstat/mcstat.cc

@@ -62,7 +62,7 @@ static bool request_dcp_stat(MemcachedConnection& connection,
                                            "{}_{} {}\n",
                                            key,
                                            iter.key(),
-                                           iter.value());
+                                           iter.value().dump());
                             }
                         } else {
                             fmt::print(stdout, "{} {}\n", key, value);