IPv6 Resolver Fix

[tfmm]

Issue
Currently IPv6 resolvers defined in resolv.conf are being added to /etc/nginx/conf.d/includes/resolvers.conf in plain text. Nginx requires IPv6 resolvers to be enclosed by [].

Issue is present at the very least when running container with Podman, unsure if present when running with Docker.

Describe the solution you'd like
Created PR to fix: #246