OpenSSL 3.0 made EVP_PKEY immutable. This means we can only have a const
pointer of the low level struct and the following methods can no longer
be provided when linked against OpenSSL 3.0:

 - OpenSSL::PKey::RSA#set_key
 - OpenSSL::PKey::RSA#set_factors
 - OpenSSL::PKey::RSA#set_crt_params
 - OpenSSL::PKey::DSA#set_pqg
 - OpenSSL::PKey::DSA#set_key
 - OpenSSL::PKey::DH#set_pqg
 - OpenSSL::PKey::DH#set_key
 - OpenSSL::PKey::EC#group=
 - OpenSSL::PKey::EC#private_key=
 - OpenSSL::PKey::EC#public_key=

There is no direct replacement for this functionality at the moment.
I plan to introduce a wrapper around EVP_PKEY_fromdata(), which takes
all key components at once to construct an EVP_PKEY.

https://github.com/ruby/openssl/commit/6848d2d969