Adding webp to regex list. Added function return type for consistency with the rest of the functions (#7649)

src/lib/media/util.ts

···
   return Math.round((uri.length * 3) / 4)
 }
 
-export function isUriImage(uri: string) {
-  return /\.(jpg|jpeg|png).*$/.test(uri)
+export function isUriImage(uri: string): boolean {
+  return /\.(jpg|jpeg|png|webp).*$/.test(uri)
 }
 
 export function blobToDataUri(blob: Blob): Promise<string> {