redifinition of struct hash<coroutine_handle<_Tp> >

### Search before asking

- [x] I searched the [issues](https://github.com/alibaba/async_simple/issues) and found no similar issues.

### What happened + What you expected to happen
I'm on MacOS and I use g++-11 (11.2.0) for both CXX and CC. I come across the error when build.
```
/async_simple/async_simple/experimental/coroutine.h:400:8: error:
redefinition of 'hash >'
struct hash > {
/include/c++/v1/experimental/coroutine:323:8: note:
previous definition is here
struct hash<_VSTD_CORO::coroutine_handle<_Tp> > {
```

### Reproduction way

### Anything else

### Are you willing to submit a PR?

- [ ] Yes I am willing to submit a PR!