Use explicit width and height in widget

[Frode]

Suggestion from GTMetrix:
Set an explicit width and height on image elements to reduce layout shifts and improve CLS.

I am getting this on the images I have in my SC featured widget carusel on the forum index.

	div.contentRow-main > div.contentRow-figure > a > img <img src="/data/showcase_covers/0/8.jpg">
	div.contentRow-main > div.contentRow-figure > a > img <img src="/data/showcase_covers/0/6.jpg">
	div.contentRow-main > div.contentRow-figure > a > img <img src="/data/showcase_covers/0/10.jpg">
	div.contentRow-main > div.contentRow-figure > a > img <img src="/data/showcase_covers/0/9.jpg">