fix: Add StickerGif compatibility with Webp format (#278)

It works the same as gif files, and has the same color loss problem as gifs:
#277 (comment)

README.md

@@ -387,7 +387,7 @@ await client
   });
 
 // Generates sticker from the provided animated gif image and sends it (Send image as animated sticker)
-// image path imageBase64 A valid gif image is required. You can also send via http/https (http://www.website.com/img.gif)
+// image path imageBase64 A valid gif and webp image is required. You can also send via http/https (http://www.website.com/img.gif)
 await client
   .sendImageAsStickerGif('000000000000@c.us', './image.gif')
   .then((result) => {

src/api/layers/sender.layer.ts

@@ -514,13 +514,13 @@ export class SenderLayer extends ListenerLayer {
    *  @param to chatId '000000000000@c.us'
    */
   public async sendImageAsStickerGif(to: string, path: string) {
-    let b64 = await downloadFileImgHttp(path, ['image/gif']);
+    let b64 = await downloadFileImgHttp(path, ['image/gif', 'image/webp']);
     if (!b64) {
       b64 = await fileToBase64(path);
     }
     if (b64) {
       const buff = Buffer.from(
-        b64.replace(/^data:image\/(gif);base64,/, ''),
+        b64.replace(/^data:image\/(gif|webp);base64,/, ''),
         'base64'
       );
       const mimeInfo = base64MimeType(b64);