CentOS 7 strikes again:

lib/transport/tls-context.c: In function 'tls_context_setup_ssl_version':
lib/transport/tls-context.c:205:3: warning: implicit declaration of function 'SSL_CTX_set_min_proto_version' [-Wimplicit-function-declaration]
   SSL_CTX_set_min_proto_version(self->ssl_ctx, self->ssl_version);
   ^
lib/transport/tls-context.c: In function 'tls_context_set_ssl_version_by_name':
lib/transport/tls-context.c:691:25: error: 'TLS1_3_VERSION' undeclared (first use in this function)
     self->ssl_version = TLS1_3_VERSION;

SSL_CTX_set_min_proto_version docs say:

The setter functions were added in OpenSSL 1.1.0. The getter functions were added in OpenSSL 1.1.1.

But the default version is 1.0.2 (), however there seems to be an EPEL package for 1.1.1: https://src.fedoraproject.org/rpms/openssl11.
I haven't tried it, just found it, but it seems that it has not been updated for a while (1.1.1k [25 Mar 2021] instead of the latest 1.1.1w [11 Sep 2023]).

Taking into account that the package is not up-to-date and the fact that CentOS 7 becomes EOL on June 30, 2024, I am not sure if it would be worth adding support for it, what do you think Bazsi?

@OverOrion thanks for the review. I've now fixed up CentOS7 support so all should be good now.