ci: correctly delete the head branch (#388)

scripts/bump-version.mjs

@@ -85,7 +85,7 @@ if (previousPullRequest) {
 	await octokit.request('DELETE /repos/{owner}/{repo}/git/refs/{ref}', {
 		owner: OWNER,
 		repo: REPOSITORY,
-		ref: `heads/chore/release/${newVersion['discord-api-types']}`,
+		ref: `heads/${previousPullRequest.head.ref}`,
 	});
 
 	console.log(`✅ Done. Pull request ${previousPullRequest.number} was closed and will be recreated.`);