Remove C++ flags from xmake configuration

Removed unnecessary C++ flags from build configuration.

Author: user-grinch

.github/workflows/build.yml

@@ -85,7 +85,6 @@ jobs:
           --mingw=/usr \
           --cc=clang-23 \
           --cxx=clang++-23 \
-          --cxxflags="-stdlib=libc++ -std=c++2b" \
           -c -y
         xmake -j$(nproc)