chore: Enable clang-tidy modernize-use-nodiscard check (#7015)

src/test/jtx/impl/WSClient.cpp

@@ -281,7 +281,7 @@ public:
         return std::move(m->jv);
     }
 
-    unsigned
+    [[nodiscard]] unsigned
     version() const override
     {
         return rpc_version_;