Posibility to set cipher_suites

I am using the node-cert-exporter in an environment where ports are scanned for weak cipher settings. In the regular node_exporter, there is an option flag --web.config.file="" that allows specifying ciphers that are not recommended for use.

Please consider adding this option to the node-cert-exporter as well.

For reference, here is the node_exporter documentation:
https://github.com/prometheus/exporter-toolkit/blob/master/docs/web-configuration.md

ps. --web.config.fil might also be useful for other setup purposes.