Apply clang-tidy fixes for readability-container-size-empty in Serial…

…izeToLLVMBitcode.cpp (NFC)

mlir/unittests/Target/LLVM/SerializeToLLVMBitcode.cpp

@@ -60,7 +60,7 @@ TEST_F(MLIRTargetLLVM, SKIP_WITHOUT_NATIVE(SerializeToLLVMBitcode)) {
                                   "");
   std::optional<SmallVector<char, 0>> serializedModule = serializer.run();
   ASSERT_TRUE(!!serializedModule);
-  ASSERT_TRUE(serializedModule->size() > 0);
+  ASSERT_TRUE(!serializedModule->empty());
 
   // Read the serialized module.
   llvm::MemoryBufferRef buffer(