Use secure TLS/SSL versions:

TLS1.2 can be used instead, it is available in all currently
supported versions of OpenSSL.

Signed-off-by: Damian Jarek <damian.jarek93@gmail.com>

example/http/server/stackless-ssl/http_server_stackless_ssl.cpp

@@ -308,7 +308,7 @@ public:
     }
 
     #include <boost/asio/yield.hpp>
-    
+
     void
     loop(
         beast::error_code ec,
@@ -465,7 +465,7 @@ public:
 private:
 
     #include <boost/asio/yield.hpp>
-    
+
     void
     loop(beast::error_code ec = {})
     {
@@ -523,7 +523,7 @@ int main(int argc, char* argv[])
     net::io_context ioc{threads};
 
     // The SSL context is required, and holds certificates
-    ssl::context ctx{ssl::context::sslv23};
+    ssl::context ctx{ssl::context::tlsv12};
 
     // This holds the self-signed certificate used by the server
     load_server_certificate(ctx);