gateway: remove actions/setup-go from explicit allowlist

[raboof]

as actions/* is already implicitly allowed

Request for adding a new GitHub Action to the allow list

Overview

Name of action:

URL of action:

Version to pin to (hash only):

Permissions

Related Actions

Checklist

You should be able to check most of these boxes for an action to be considered for review.
Please check all boxes that currently apply:

• The action is listed in the GitHub Actions Marketplace
• The action is not already on the list of approved actions
• The action has a sufficient number of contributors or has contributors within the ASF community
• The action has a clearly defined license
• The action is actively developed or maintained
• The action has CI/unit tests configured