FileFactory can't create gif files

[AmirRezaM75]

• Laravel Version: 8.43.0
• PHP Version: 7.4.20
• Database Driver & Version: MySQL 8.0

Steps To Reproduce:

I needed to create image file with gif extension in my tests.

$this->post('dashboard/media', [
    'image' => UploadedFile::fake()->image('example.gif')
])->assertRedirect('dashboard/media');

I get image file using $request->file('image') and save it in storage disk.
It saves the file with correct extension but when I'm using mime_content_type, it returns image/png.

Description:

I scanned the code base and I noticed we can only create jpeg or png files with this class.

framework/src/Illuminate/Http/Testing/FileFactory.php

Lines 57 to 59 in 952f84a

	return new File($name, $this->generateImage(
	$width, $height, Str::endsWith(Str::lower($name), ['.jpg', '.jpeg']) ? 'jpeg' : 'png'
	));

[driesvints]

Seems like a feature request. Seems like you already attempted a pr. Thanks.