OpenSSL deprecation warning

[sergey-safarov]

On a fresh dist lot of warning about OpenSSL deprecated function call.

iles/ks2.dir/src/ks_ssl.c.o -MF CMakeFiles/ks2.dir/src/ks_ssl.c.o.d -o CMakeFiles/ks2.dir/src/ks_ssl.c.o -c /tmp/libks/src/ks_ssl.c
/tmp/libks/src/ks_ssl.c: In function ‘mkcert’:
/tmp/libks/src/ks_ssl.c:211:5: warning: ‘RSA_new’ is deprecated: Since OpenSSL 3.0 [-Wdeprecated-declarations]
  211 |     rsa = RSA_new();
      |     ^~~
In file included from /usr/include/openssl/x509.h:36,
                 from /usr/include/openssl/ssl.h:31,
                 from /tmp/libks/src/include/libks/ks_ssl.h:25,
                 from /tmp/libks/src/include/libks/ks.h:80,
                 from /tmp/libks/src/ks_ssl.c:23:
/usr/include/openssl/rsa.h:206:28: note: declared here
  206 | OSSL_DEPRECATEDIN_3_0 RSA *RSA_new(void);
      |                            ^~~~~~~
/tmp/libks/src/ks_ssl.c:220:9: warning: ‘RSA_generate_key_ex’ is deprecated: Since OpenSSL 3.0 [-Wdeprecated-declarations]
  220 |         RSA_generate_key_ex(rsa, bits, BN_value_RSA_F4, NULL);
      |         ^~~~~~~~~~~~~~~~~~~
/usr/include/openssl/rsa.h:265:27: note: declared here
  265 | OSSL_DEPRECATEDIN_3_0 int RSA_generate_key_ex(RSA *rsa, int bits, BIGNUM *e,
      |                           ^~~~~~~~~~~~~~~~~~~
/tmp/libks/src/ks_ssl.c:227:9: warning: ‘EVP_PKEY_assign’ is deprecated: Since OpenSSL 3.0 [-Wdeprecated-declarations]
  227 |         if (!EVP_PKEY_assign_RSA(pk, rsa)) {
      |         ^~
In file included from /usr/include/openssl/x509.h:29:
/usr/include/openssl/evp.h:1328:5: note: declared here
 1328 | int EVP_PKEY_assign(EVP_PKEY *pkey, int type, void *key);
      |     ^~~~~~~~~~~~~~~