Add pa11y-ci for accesibility linting

[TrialDragon]

This adds a new CI job for pa11y-ci in order to automate checking if the site, or PR to the site, satisfies basic accessibility guidelines.

Closes #396

[TrialDragon]

Mm, switching to echo broke it further. Edit: Fixed it with the -e argument. Also there is probably still the puppeteer issue regarding the chrome executable. I'll continue work on this tomorrow. (Open to suggestions regarding causes and fixes for this.)

[TrialDragon]

It's working finally! Now to actually solve the accessibility issues—after #1026 is merged since it already solves some of the issues with image height width attributes and alt text.

[BD103]

There's a chance a lot of the accessibility errors are duplicated, since we use templates. I know there are also a few dead pages with the Zola welcome page. If those can be removed, CI times should decrease.

Does pa11y-ci run Chrome for accessibility checking? Is there an alternative tool that doesn't take as much time?

[TrialDragon]

There's a chance a lot of the accessibility errors are duplicated, since we use templates. I know there are also a few dead pages with the Zola welcome page. If those can be removed, CI times should decrease.

Does pa11y-ci run Chrome for accessibility checking? Is there an alternative tool that doesn't take as much time?

Yes, it does run Chrome via Puppeteer. There are alternative tools; they're paid / cost money. (Axe by Deque, and AccessLint). The latter can be technically free for personal accounts, but not for our use case afaik. To my knowledge pa11y is the one free tool in this sector. (Maybe ESLint has somethings, but it's not a dedicated accessibility lint and I couldn't find good info on it).

The dead pages should be gotten rid of with ... o, damn, the PR that fixed those things was closed. (#601). I guess I can open up a new one to get rid of the whole improper use of pages for community stuff that plagues us.

Some of the issues are being duplicated due to templates, yes. Not sure if there is a good way to solve it.

[BD103]

The dead pages should be gotten rid of with ... o, damn, the PR that fixed those things was closed. (#601). I guess I can open up a new one to get rid of the whole improper use of pages for community stuff that plagues us.

Yes, that would be awesome! There's quite a few: I recommend building the website and grep-ing Welcome to Zola! to find all of the pages. Ones being built for each Bevy Asset, error, people page, donation page, and probably more.

Some of the issues are being duplicated due to templates, yes. Not sure if there is a good way to solve it.

Unfortunately I don't think it's something that can be solved. My point was just that some errors may be overly-inflated due to duplicated HTML.

[TrialDragon]

Next step is to actually add the dummy files meant to represent the generic assets section, examples section, example page, community things, et cetera. Just removing the dependencies now to gauge how fast this will be approximately.

[TrialDragon]

Okay, it should now cover all the areas without having to wait for things to be generated. Will fix the actual accessibility issues it catches later, after #1026 is merged, or closed, in the indeterminate future.

[TrialDragon]

Okay, looking thru the complaints the CI is now officially complaining about the invalid pages. So, uh, I guess this is blocked from merging until that's dealt with.

[TrialDragon]

Okay last two issues is getting rid of invalid pages and adding aria labels to the image comparing widget. I'll wait until the shortcode in #710 is merged so that stuff isn't being unnecessarily repeated creating merge conflicts that could be avoided.

[SIGSTACKFAULT]

@TrialDragon I adopted #710 and shortcodes were merged in #1144
If I'd known about this I would have added labels >.<