Compiler warnings on free-threaded build for `_hashopenssl.c`

[picnixz]

Bug report

Bug description:

I get the following warnings since #128886, which was backported to 3.13.

./Modules/_hashopenssl.c:416:69: warning: passing 'const EVP_MD *' (aka 'const struct evp_md_st *') to parameter of type 'void *' discards qualifiers [-Wincompatible-pointer-types-discards-qualifiers]
  416 |                 other_digest = _Py_atomic_exchange_ptr(&entry->evp, digest);
      |                                                                     ^~~~~~
./Include/cpython/pyatomic_gcc.h:194:42: note: passing argument to parameter 'value' here
  194 | _Py_atomic_exchange_ptr(void *obj, void *value)
      |                                          ^
./Modules/_hashopenssl.c:428:80: warning: passing 'const EVP_MD *' (aka 'const struct evp_md_st *') to parameter of type 'void *' discards qualifiers [-Wincompatible-pointer-types-discards-qualifiers]
  428 |                 other_digest = _Py_atomic_exchange_ptr(&entry->evp_nosecurity, digest);
      |                                                                                ^~~~~~
./Include/cpython/pyatomic_gcc.h:194:42: note: passing argument to parameter 'value' here
  194 | _Py_atomic_exchange_ptr(void *obj, void *value)

CPython versions tested on:

CPython main branch

Operating systems tested on:

No response

Linked PRs

• gh-132674: fix _hashopenssl.c warnings on free-threaded build #132675
• [3.13] gh-132674: fix _hashopenssl.c compiler warnings on free-threaded build (GH-132675) #132677

[colesbury]

I think _Py_atomic_exchange_ptr() should take a const void * as the second argument instead of void *.