Add inet6 rule to pf.conf template

[ddowse]

The new rules will allow ine6 traffic passing the pf as well. Preventing accidental lockout/block of connection to target over ipv6.

[yaazkal]

Thanks for the PR!
I do think that just removing the inet word will support both IPv4 and IPv6, inet was more like a restriction. That way we can avoid line duplication and end up with a simpler file.

Do you mind to test if it works?
Something like:

antispoof for $ext_if
pass in proto tcp from any to any port ssh flags S/SA keep state