Remove std::move of trivially-copyable type.

Address ClangTidy finding:

* std::move of the expression of the trivially-copyable type 'mlir::Module' (aka 'mlir::ModuleOp') has no effect; remove std::move()

PiperOrigin-RevId: 256981849

mlir/examples/toy/Ch2/mlir/MLIRGen.cpp

@@ -87,7 +87,7 @@ public:
       return nullptr;
     }
 
-    return std::move(theModule);
+    return theModule;
   }
 
 private: