update MediaItem to suport dynamic size

* this is needed for dynamic span count to correctly work
* this also fixes issues with poster image cropping when the MediaItem size was < 195dp

app/src/main/java/org/mosad/teapod/util/adapter/MediaItemListAdapter.kt

@@ -36,7 +36,7 @@ class MediaItemListAdapter(private val onClickListener: OnClickListener) : ListA
         fun bind(item: ItemMedia) {
             binding.textTitle.text = item.title
 
-            Glide.with(binding.imagePoster)
+            Glide.with(binding.root.context)
                 .load(item.posterUrl)
                 .into(binding.imagePoster)