`pr_fetch()` missing escaping

[hadley]

Due to PR titled list {duckplyr} on packages page

[jennybc]

Some guidance for someone who picks this up on tidyverse dev day:

The problem is happening in this neighborhood:

usethis/R/pr.R

Lines 986 to 1003 in 00552bb

	pr_pretty <- purrr::pmap_chr(
	pr_dat[c("pr_number", "pr_html_url", "pr_user", "pr_state", "pr_title")],
	function(pr_number, pr_html_url, pr_user, pr_state, pr_title) {
	href_number <- ui_pre_glue("{.href [PR #<<pr_number>>](<<pr_html_url>>)}")
	at_user <- glue("@{pr_user}")
	if (some_closed) {
	template <- ui_pre_glue(
	"<<href_number>> ({.field <<at_user>>}, {pr_state}): {.val <<pr_title>>}"
	)
	cli::format_inline(template)
	} else {
	template <- ui_pre_glue(
	"<<href_number>> ({.field <<at_user>>}): {.val <<pr_title>>}"
	)
	cli::format_inline(template)
	}
	}
	)

And stems from a pr_title that contains curly braces.

You'll need to use techniques described here to guard against this:

https://cli.r-lib.org/reference/inline-markup.html#escaping-and-

Also look around for other uses of pr_title in this file and see if they also need the same fix.