Enclose failing spec in single quotes

So that when copy pasting it, zsh won't complain with "zsh: no matches found" error due to presence of unescaped `[]` in the command.

[skip ci]

script/github_pr_errors

@@ -80,5 +80,5 @@ get_json(last_test_action['jobs_url'])
 if errors.empty?
   warn "No rspec errors found :-/"
 else
-  puts errors.flatten.uniq.join(" ")
+  puts errors.flatten.uniq.map { "'#{_1}'" }.join(" ")
 end