Release 2.6 version for CVE-2023-4863

CVE-2023-4863 fixed version

• libwebp 1.3.2 updated in previous v2.4
• Add an option for static webp decoder in library to workaround CVE-2023-4863 in android framework

WebpBitmapFactory.sUseSystemDecoder = false;    // disable system decoder global first
Transformation<Bitmap> circleCrop = new CircleCrop();
GlideApp.with(mContext)
        .load(url)
        .optionalTransform(circleCrop)
        .optionalTransform(WebpDrawable.class, new WebpDrawableTransformation(circleCrop))
        .set(WebpDownsampler.USE_SYSTEM_DECODER, false) // disable system decoder for each request
        .into(imageView);