Add fallback for devices without WebP support
In the latest nitter release, images in tweets do not display any more in some browsers, and as there’s no image size given in the <img> element, there’s no placeholder shown either to realize that something's missing (and to click on it to open the file separately).

Example: https://nitter.net/pic/media%2Fsomething.jpg%3Fname%3Dsmall%26format%3Dwebp 
(The delivered file is in webp format.)

As the issue is not present in tweets that still deliver small images in png format (like from quoted tweets), it might be the webp format. There’s still quite a lot of devices and (unupdateable) browsers that do not support webp: https://caniuse.com/webp

Was there a change to display the small size images in webp rather than jpg and png? If yes, could you please consider reverting to jpg or png by default? Otherwise, nitter cannot be used by these browsers/devices and more. Thanks

 (Escaping URL chars that appear in their special role might also not be the best idea, although it seems to work.)