fix: link checker

[lechnerc77]

Purpose

• Add link to gnu.org to skipped links as there seems to be a rate limting issue
• Closes Link Checker Report #908

Does this introduce a breaking change?

[ ] Yes
[X] No

Pull Request Type

What kind of change does this Pull Request introduce?

[ ] Bugfix
[ ] Feature
[ ] Refactoring (no functional changes, no api changes)
[ ] Documentation content changes
[X] Other... Please describe: repo setup

How to Test

• Execute GH Action for Link Checking

What to Check

Verify that the following are valid:

• Link check pass

Other Information

n/a

Checklist for reviewer

The following organizational tasks must be completed before merging this PR:

• The PR is assigned to the Terraform project and a status is set (typically "in review").
• The PR has the matching labels assigned to it.
• The PR has a milestone assigned to it.
• If the PR closes an issue, the issue is referenced.
• Possible follow-up items are created and linked.

[lechnerc77]

Override as only link checks are concerned