Allow resolver with custom dns port.

[simoneaster]

Describe the issue you are having

Port doesn't appear to be configurable when specifying resolver.

How are you running the container(s)

proxy:
image: lancachenet/sniproxy
environment:
- UPSTREAM_DNS=a.b.c.d:5053
ports:
- 80:80
- 443:443

DNS Configuration

attempting to use env var redirecting to dns on a custom port.

Output of container(s)

sniproxy unable to resolve when custom port is attempted?