fix: also publish setup.js (#591)

## PR Checklist

- [x] Addresses an existing open issue: fixes #588
- [x] That issue was marked as [`status: accepting
prs`](https://github.com/JoshuaKGoldberg/console-fail-test/issues?q=is%3Aopen+is%3Aissue+label%3A%22status%3A+accepting+prs%22)
- [x] Steps in
[CONTRIBUTING.md](https://github.com/JoshuaKGoldberg/console-fail-test/blob/main/.github/CONTRIBUTING.md)
were taken

## Overview

Adds it to the `package.json` `"files"` list, and also adds an
`"exports"` entry for it.

Author: JoshuaKGoldberg

package.json

@@ -22,14 +22,16 @@
 				"types": "./lib/index.d.cts",
 				"default": "./lib/index.cjs"
 			}
-		}
+		},
+		"./setup": "./setup.js"
 	},
 	"main": "./lib/index.js",
 	"files": [
 		"lib/",
-		"package.json",
 		"LICENSE.md",
-		"README.md"
+		"package.json",
+		"README.md",
+		"setup.js"
 	],
 	"scripts": {
 		"build": "tsup",