Update acknowledgement

Author: Yikai-Liao

README.md

@@ -90,3 +90,4 @@ pip install ./symusic
 * [nanobind](https://github.com/wjakob/nanobind) : A efficient and lightweight library for binding C++ to Python, which is significantly faster than [pybind11](https://github.com/pybind/pybind11).
 * [zpp_bits](https://github.com/eyalz800/zpp_bits) : An extraordinary fast and lightweight single header library for serialization and deserialization. I use it to support pickle.
 * [geek_time_cpp](https://github.com/adah1972/geek_time_cpp/tree/master) The example code of the book "Modern C++ Programming Practice". We use the [metamacro.h](https://github.com/adah1972/geek_time_cpp/blob/master/40/metamacro.h#L1-L622) in it for shortening the code.
+* [utfcpp](https://github.com/nemtrif/utfcpp) An easy to use and portable library for handling utf8 string in C++.