A lot of content is generated in `/tmp`

[ggenzone]

The intermediate files that are downloaded are stored in /tmp, which makes it use a lot of space unnecessarily.

You could add a call to the unlink function to delete the file after use and this would improve a lot and avoid the need to go around deleting temporary files.

In this line:
https://github.com/wgenial/s3-objects-stream-zip-php/blob/master/src/S3ObjectsStreamZip.php#L69

        ....
        $tmpfile = tempnam(sys_get_temp_dir(), crc32(time()));

        $httpClient->request("GET", (string) $request->getUri(), array(
          "synchronous" => true,
          "sink" => fopen($tmpfile, "w+")
        ));
        
        if ($stream = fopen($tmpfile, "r", false, $context)) {
          $zip->addFileFromStream($objectName, $stream);
        }
        
        unlink($tmpfile);   // <-- This line will tell PHP that we no longer need the file.
      }