github-export-2.php

<?php
 
function page($page = 1) {
    $request = (new \GuzzleHttp\Client())
        ->get('https://api.github.com/repos/user/repo/pulls', [
            'auth' => ['username', 'password'],
            'headers' => [
                'User-Agent' => 'CSV export',
                'Accept' => 'application/vnd.github.v3+json',
            ],
            'query' => [
                'since' => '2016-06-01T00:00:00Z',
                'state' => 'all',
                'per_page' => 100,
                'page' => $page
            ],
        ]);

    return json_decode($request->getBody()->getContents());
}

Route::get('csv', function() {
    $pages = 2;

    header('Content-Type: application/excel');
    header('Content-Disposition: attachment; filename=github-isuses.csv');

    $fp = fopen('php://output', 'w');
    fputcsv($fp, [
        'ID',
        'Title',
        'Created Date',
        'Updated Date',
        'Closed Date',
        'Merged Date',
    ]);

    for ($i = 1; $i <= ($pages+1); $i++) {
        $new = page($i);

        foreach($new AS $item) {
            fputcsv($fp, [
                $item->number,
                $item->title,
                $item->created_at,
                $item->updated_at,
                $item->closed_at,
                $item->merged_at,
            ]);
        }
    }
    fclose($fp);
});

Typo: filename=github-isuses.csv