Fix TF re-adding annotations on every apply

[sl1pm4t]

Fixes #72

This fixes an issue that could cause Terraform to attempt to re-apply certain annotations on every run.
This fix already applied to top level annotations, but needed to be added to annotations within a PodTemplate (i.e nested inside a Deployment, DaemonSet, StatefulSet spec)

Before the fix, the modified Deployment test case fails with:

--- FAIL: TestAccKubernetesDeployment_with_template_metadata (69.35s)
    testing.go:518: Step 0 error: After applying this step, the plan was not empty:

        DIFF:

        UPDATE: kubernetes_deployment.test
          spec.0.template.0.metadata.0.annotations.%:                              "3" => "4"
          spec.0.template.0.metadata.0.annotations.kubernetes.io/egress-bandwidth: "" => "1M"

After the change:

--- PASS: TestAccKubernetesDeployment_with_template_metadata (135.66s)
PASS