mainmenu: Tidy up logic in is_server_protocol_compat() (#3997)

Apply de morgan to simplify the logic.

builtin/mainmenu/common.lua

@@ -290,7 +290,7 @@ end
 
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 function is_server_protocol_compat(server_proto_min, server_proto_max)
-	return not ((min_supp_proto > (server_proto_max or 24)) or (max_supp_proto < (server_proto_min or 13)))
+	return min_supp_proto <= (server_proto_max or 24) and max_supp_proto >= (server_proto_min or 13)
 end
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 function is_server_protocol_compat_or_error(server_proto_min, server_proto_max)