Images not showing up in Pull request helpers article

[jonbry]

I noticed that the Pull request helpers article appears to be missing some images. For example, I think there should be an image shown here:

usethis/vignettes/articles/pr-functions.Rmd

Lines 138 to 145 in 8d3979c

	```{r, echo = FALSE}
	#| fig-alt: Screenshot of the RStudio Git pane showing the file
	#| R/adjective.R staged for a commit. The preview of the file
	#| highlights the addition of the line "formidabel", with no comma
	#| at the end of the line. The Commit message says
	#| "Add 'formidable' to adjectives".
	knitr::include_graphics("img/pr-functions-diff.png", dpi = 300)
	```

This is what I see on the website:

I was able to reproduce this across multiple devices and browsers.

[jennybc]

I don't think my solution is truly correct, but I could not quickly figure out why the quotes in the alt text are causing problems, when they did not in the past. It feels like a change elsewhere in the knitr/pkgdown stack and I don't have time to get to the bottom of it right now. Just removing quotes seemed like a decent bandaid.

[jennybc]

Note the fix will only show up in the dev site until the next usethis release (or I make some explicit effort to backport this fix).