bpo-40479: Fix hashlib issue with OpenSSL 3.0.0 (GH-20107)

OpenSSL 3.0.0-alpha2 was released today. The FIPS_mode() function has
been deprecated and removed. It no longer makes sense with the new
provider and context system in OpenSSL 3.0.0.

EVP_default_properties_is_fips_enabled() is good enough for our needs in
unit tests. It's an internal API, too.

Signed-off-by: Christian Heimes <christian@python.org>