v1.18: ci: ignore the tonic audit as a temporary stopgap (backport of #3052)

[mergify]

Problem

I'm too naive. #3050 will take some time to upgrade. use this quick fix for unblocking master asap

Summary of Changes

ignore tonic audit report temporarily

---

This is an automatic backport of pull request #3052 done by [Mergify](https://mergify.com).

[mergify]

Cherry-pick of 9b5525d has failed:

On branch mergify/bp/v1.18/pr-3052
Your branch is up to date with 'origin/v1.18'.

You are currently cherry-picking commit 9b5525d127.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   ci/do-audit.sh

no changes added to commit (use "git add" and/or "git commit -a")

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

[willhickey]

Need to tag another v1.18 release but it won't build without this change