`acorn login` and `acorn credentials` don't work after logging out of acorn.io

[njhale]

Description

acorn login <server> and acorn credentials fail and return the following message when the CLI isn't logged in to acorn.io:

  ✗  ERROR:  failed to get API group resources: unable to retrieve the complete list of server APIs: api.acorn.io/v1: Get "https://127.0.0.1:6443/apis/api.acorn.io/v1": tls: failed to verify certificate: x509: certificate signed by unknown authority

Reproduction Steps

1. acorn login
2. acorn logout
3. acorn credentials or acorn login <not-acorn.io>

Impact

This bug prevents users of the CLI from checking remote and local credentials as well as logging into acorn servers other than acorn.io.