Fix updates of stateful set images

[pdecat]

Images used for container in Stateful Set templates cannot be updated.

TODO:

• add acceptance test
• fix issue

Acceptance test result without fix:

# make testacc TEST=./kubernetes TESTARGS='-run=TestAccKubernetesStatefulSet_update_image -count=1'
==> Checking that code complies with gofmt requirements...
TF_ACC=1 go test ./kubernetes -v -run=TestAccKubernetesStatefulSet_update_image -count=1 -timeout 120m
=== RUN   TestAccKubernetesStatefulSet_update_image
--- FAIL: TestAccKubernetesStatefulSet_update_image (3.01s)
        testing.go:518: Step 1 error: Check failed: 1 error(s) occurred:

                * Check 2/2 error: kubernetes_stateful_set.test: Attribute 'spec.0.template.0.spec.0.container.0.image' expected "k8s.gcr.io/liveness:latest", got "k8s.gcr.io/pause:latest"
FAIL
FAIL    github.com/terraform-providers/terraform-provider-kubernetes/kubernetes 3.059s
make: *** [GNUmakefile:17: testacc] Error 1

[pdecat]

Acceptance test results with fix:

# make testacc TEST=./kubernetes TESTARGS='-run=TestAccKubernetes\(StatefulSet\).* -count=1'
==> Checking that code complies with gofmt requirements...
TF_ACC=1 go test ./kubernetes -v -run=TestAccKubernetes\(StatefulSet\).* -count=1 -timeout 120m
=== RUN   TestAccKubernetesStatefulSet_basic
--- PASS: TestAccKubernetesStatefulSet_basic (1.81s)
=== RUN   TestAccKubernetesStatefulSet_basic_idempotency
--- PASS: TestAccKubernetesStatefulSet_basic_idempotency (1.94s)
=== RUN   TestAccKubernetesStatefulSet_update_image
--- PASS: TestAccKubernetesStatefulSet_update_image (2.88s)
=== RUN   TestAccKubernetesStatefulSet_update_template_selector_labels
--- PASS: TestAccKubernetesStatefulSet_update_template_selector_labels (2.64s)
=== RUN   TestAccKubernetesStatefulSet_update_replicas
--- PASS: TestAccKubernetesStatefulSet_update_replicas (2.40s)
=== RUN   TestAccKubernetesStatefulSet_update_rolling_update_partition
--- PASS: TestAccKubernetesStatefulSet_update_rolling_update_partition (2.40s)
=== RUN   TestAccKubernetesStatefulSet_update_update_strategy_on_delete
--- PASS: TestAccKubernetesStatefulSet_update_update_strategy_on_delete (2.35s)
=== RUN   TestAccKubernetesStatefulSet_update_update_strategy_rolling_update
--- PASS: TestAccKubernetesStatefulSet_update_update_strategy_rolling_update (2.35s)
=== RUN   TestAccKubernetesStatefulSet_update_pod_template_container_port
--- PASS: TestAccKubernetesStatefulSet_update_pod_template_container_port (2.59s)
PASS
ok      github.com/terraform-providers/terraform-provider-kubernetes/kubernetes 21.400s

[pdecat]

The parameters passed to patchPodSpec were swapped: https://github.com/terraform-providers/terraform-provider-kubernetes/pull/252/files#diff-14a25dc6896cc8eaf7d1a5bcaa4da883R270

@alexsomesan PTAL

[alexsomesan]

Change looks great! Thanks for catching this and adding the safeguard test.
Please remove the test.yaml that accidentally got picked up by git and then we can merge.