`DISABLE_IPV6` should also set `ipv6=off` in the `resolvers.conf`

[czocher]

Checklist

• Have you pulled and found the error with jc21/nginx-proxy-manager:latest docker image?
  • Yes
• Are you sure you're not using someone else's docker image?
  • Yes
• Have you searched for similar issues (both open and closed)?
  • Yes

Describe the bug
When running under podman on a dns-enabled network, the internal container name is resolved correctly by the container (tested using ping {container-name}), but is not resolved correctly by nginx. Adding ipv6=off to the resolvers.conf fixes the issue. In my opinion this setting should automatically be added when setting the DISABLE_IPV6 environmental variable to true.

Nginx Proxy Manager Version
v2.9.18

To Reproduce
Steps to reproduce the behavior:

1. Create a podman container for nginx-proxy-manager with its own network (required for DNS resolving to be enabled by default) and the DISABLE_IPV6 environmental variable set to true.
2. Create another container on the same network.
3. Use the container name to create a proxy setting.
4. Nginx doesn't resolve the container by name although the container is visible and pingable.
5. Add the ipv6=off setting to the the /etc/nginx/conf.d/include/resolvers.conf for the internal DNS.
6. Reload the configuration with nginx -s reload.
7. The problem disappears.

Expected behavior
Adding DISABLE_IPV6='true' to the container config should add the ipv6=off setting to the resolvers.conf.

Operating System
Fedora CoreOS 36