imagick driver: 'format' method issue

[lightsuner]

Hello Spatie,

Thanks for the library!

---

Issue

I've come across different behaviours of gd and imagick drivers.

• My goal was to resize JPEG and save it as avif.
• Also, I wanted to use php functionality for temporary files - tmpfile().

tmpfile() - creates a file without an extension, like: /tmp/phpFx0513a.

So here is a code example:

$driver = 'imagick'; // or 'gd'
$image = SpatieImage::useImageDriver($driver)->loadFile('/path/to/original/image.jpeg');
$image->resize(100, 150);

$tmpFile = tmpfile();
$tmpFilePath = stream_get_meta_data($tmpFile)['uri'];

$image->format('avif')->save($tmpFilePath);

• So when the $driver is gd, everything works as expected.
• When the $driver is imagick, I receive the following error:

  Spatie\Image\Exceptions\UnsupportedImageFormat 

  Unsupported format ``.

In my opinion, there is a bug in the imagick driver, as it tries to fetch the format from the destination file's extension and ignores the $image->format('avif') method.

Thanks.

[freekmurze]

Hi, could you submit a PR that fixes this? If possible, include a test.