fix: K8s.Client.run/2 spec missing a possible error

[icehaunter]

K8s.Client.run/2 (actually t:K8s.Client.Runner.Base.error_t/0) spec was missing t:K8s.Client.APIError.t/0 from possible error types, making code like this trigger Dialyzer warnings:

case K8s.Client.run(conn, operation) do
  {:ok, result} -> {:ok, result}
  {:error, %K8s.Client.APIError{} = error} -> # ... This case is marked as "can never match the type"
end

I'm aware that this type may actually be missing from the return union based on the chosen HTTP provider (this error is from K8s.Client.HTTPProvider.handle_kubernetes_error/1), but it is present when you're using the defaults and it would be nice to have that reflected without suppressing Dialyzer warnings at the point of use.

Requirements for all pull requests

• Entry in CHANGELOG.md was created

[mruoss]

Thanks!