fix URLs for dirhtml builds

[drammock]

closes #1675

@kathatherine can you try out this branch to see if it fixes dirhtml builds for you?

[kathatherine]

Followed most of the instructions here to set up a dev environment with your branch. Whether I build the pydata-sphinx-theme docs or my own set of docs, I get the following extension error:

Handler <function _fix_canonical_url at 0x10598cae0> for event 'html-page-context' threw an exception (exception: _fix_canonical_url() takes 3 positional arguments but 5 were given)

Uncertain if I've done something wrong or if there's an underlying issue with the branch, but it does appear that the failing tests are giving the same error.

Thanks for attempting to fix this!

[drammock]

sorry about that @kathatherine! I forgot to check back to see how the CIs did (and obviously I failed to run the tests locally before pushing 🙈). I think this change should resolve it.

FWIW you shouldn't need to set up a full PST dev environment to test on your own project; changing your project's environment to install the theme from this branch should be enough to test it out. E.g.

pip install -U https://github.com/drammock/pydata-sphinx-theme/archive/refs/heads/canonical-urls.zip

[kathatherine]

Thanks for the tip on that theme install. TIL!

This appears to get the job done for my dirhtml built docs. 🎉

I didn't notice any edge cases when clicking around. Thanks very much!

[drammock]

Team, I'll plan to self merge this one tomorrow unless someone wants extra time to review. I think it's a pretty innocuous change