Add workaround for Clang 15 compatibility in Generator.

[faker2048]

Why

Closes #372.

Changes:

• Generator.h and GeneratorTest.cpp: If the user is using Clang-15, skip compiling GeneratorTest.cpp directly and add a compilation warning in Generator.h.
• README.md and README_CN.md: Removing specific mentions of Clang-15 compiler flag workarounds.
• coro/test/CMakeLists.txt: Removed conditional compilation flags related to Clang-15.

TEST

Executed ctest on:

• Apple Clang 15
• Linux Clang 15

[faker2048]

有点奇怪，这个pr的修改不应该对 CI 用的 clang14 有任何影响

[ChuanqiXu9]

可能是代码的问题也可能是 ci 的问题，但应该和这个 patch 无关。