fix: update pkgdown.yaml

[dshemetov]

Checklist

Please:

• Make sure this PR is against "dev", not "main" (unless this is a release
  PR).
• Request a review from one of the current main reviewers:
  brookslogan, nmdefries.
• Makes sure to bump the version number in DESCRIPTION. Always increment
  the patch version number (the third number), unless you are making a
  release PR from dev to main, in which case increment the minor version
  number (the second number).
• Describe changes made in NEWS.md, making sure breaking changes
  (backwards-incompatible changes to the documented interface) are noted.
  Collect the changes under the next release number (e.g. if you are on
  1.7.2, then write your changes under the 1.8 heading).
• See DEVELOPMENT.md for more information on the development
  process.

Change explanations for reviewer

David's fix was merged into pkgdown and it was released (thank you @hadley)! r-lib/pkgdown#2406

So now we can remove the workaround in our CI.

Magic GitHub syntax to mark associated Issue(s) as resolved when this is merged into the default branch

[nmdefries]

LGTM

[dsweber2]

@nmdefries it looks like the build breaks when trying to handle slide.Rmd when documenting epi_slide_mean. It thinks it isn't defined, for some strange reason This was apparently a me problem, nevermind

[dshemetov]

I tested this locally, unfortunately after submitting this PR, and it looks like will require more work upstream with pkgdown. Going to keep this open and update when fixed.

[brookslogan]

Converted this to draft to prevent me from auto-merging before the changes mentioned above happen.