WIP: Add ssl_min_version and ssl_max_version params

[emiran-orange]

Introduce ssl_min_version and ssl_max_version params.

By default (both unset), the current behaviour stands ('TLSv1_2' is used as default in reproio/remote_syslog_sender).

This requires reproio/remote_syslog_sender#6 to be merged and remote_syslog_sender to be released.

This should close #54

[RamyaSaba]

Hi @emiran-orange ,

fluent-plugin-remote-syslog has a runtime dependency on remote_syslog_sender.
remote_syslog_sender already supports configuring the TLS protocol version via the ssl_method option, which defaults to TLSv1_2 if not provided:
@ssl_method = options[:ssl_method] || 'TLSv1_2'

However, fluent-plugin-remote-syslog does not currently expose this option or pass it through when creating the tcpSender. As a result, users cannot configure the TLS version (e.g., TLSv1_3) via Fluentd configuration, even though
the underlying sender supports it.

Would it be possible to expose ssl_method as a config_param in fluent-plugin-remote-syslog and pass it through to remote_syslog_sender?
This would allow users to explicitly configure the TLS version.