pr-preview not working correctly on webauthn PR #1663

back on 18-Jan-2022, I pushed two new commits to
https://github.com/w3c/webauthn/pull/1663 (131d68 and e1e6d94).

However, the PR preview links in the PR's original post continue to use the
earlier commit (41ffcbf) from 14-Jan-2022, even though it got the new date
correct:

```
<a href="https://pr-preview.s3.amazonaws.com/w3c/webauthn/pull/1663.html"
title="Last updated on Jan 18, 2022, 11:00 PM UTC (41ffcbf)">Preview</a> |
<a href="
https://pr-preview.s3.amazonaws.com/w3c/webauthn/1663/bc87207...41ffcbf.html"
title="Last updated on Jan 18, 2022, 11:00 PM UTC (41ffcbf)">Diff</a>
```
How do we fix this?

Also, I've noticed some other PR-preview weirdness where it may not
overwrite a prior pr-preview block in a PR's original post and instead add
the new one below the old one, so one ends up with a double set of "Preview
| Diff" links in the PR's original post.  unfortunately I presently do not
have an example I can point to for this.

thanks for any help you can provide,

=JeffH