tests: provide namesConfig = Nothing in smpServerCfg

Follow-up to the simplexmq pin bump (ee0a45e9). The new
namesConfig :: Maybe NamesConfig field on ServerConfig (introduced
in simplexmq's namespace branch) needs to appear in the test
fixture's record literal, otherwise the test suite fails to compile
under -Werror. Disabled by default (Nothing).

tests/ChatClient.hs

@@ -581,6 +581,7 @@ smpServerCfg =
       smpAgentCfg = defaultSMPClientAgentConfig,
       allowSMPProxy = True,
       serverClientConcurrency = 16,
+      namesConfig = Nothing,
       information = Nothing,
       startOptions = StartOptions {maintenance = False, compactLog = False, logLevel = LogError, skipWarnings = False, confirmMigrations = MCYesUp}
     }