Fix dns_option typo

[robbmanes]

The Podman API clarifies the field to give is dns_option, not dns_options here, so we need to drop the s to allow dns_opt fields to properly populate.

I thought about writing more unit tests for containers_create.py but there weren't existing tests for any of the options yet, so we'll have to add them for each API option I'd think.

Test program:

import json
from podman import PodmanClient

uri='unix:///run/user/1000/podman/podman.sock'

with PodmanClient(base_url=uri) as client:
    container = client.containers.create(
        image='registry.access.redhat.com/ubi8',
        command=['sleep 500'],
        dns_opt=['edns0'],
    )

Now properly works since we're passing in the right name:

$ podman --remote --url=unix://run/user/1000/podman/podman.sock ps -a
CONTAINER ID  IMAGE                                   COMMAND     CREATED        STATUS      PORTS       NAMES
211024bb2e5b  registry.access.redhat.com/ubi8:latest  sleep 500   5 seconds ago  Created                 silly_merkle

$ podman inspect silly_merkle | jq '.[].HostConfig.DnsOptions'
[
  "edns0"
]

Note that it looks like tox is failing for unrelated reasons; I'm hoping the CI will have different results and it's just a local problem.

[mheon]

@jwhonce @umohnani8 PTAL

[umohnani8]

LGTM

[jwhonce]

/lgtm

[umohnani8]

/approve

[openshift-ci]

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