fix(config.sample.php): Update enabledPreviewProviders

[provokateurin]

Synced to

server/lib/private/PreviewManager.php

Lines 277 to 291 in f951718

	$imageProviders = [
	Preview\PNG::class,
	Preview\JPEG::class,
	Preview\GIF::class,
	Preview\BMP::class,
	Preview\XBitmap::class,
	Preview\Krita::class,
	Preview\WebP::class,
	];
	$this->defaultProviders = $this->config->getSystemValue('enabledPreviewProviders', array_merge([
	Preview\MarkDown::class,
	Preview\TXT::class,
	Preview\OpenDocument::class,
	], $imageProviders));