Fix hardcoded pictrs URL reference

Reads the URL from Settings instead

lemmy_utils/src/request.rs

@@ -88,7 +88,8 @@ pub(crate) async fn fetch_pictrs(
   is_image_content_type(client, image_url).await?;
 
   let fetch_url = format!(
-    "http://pictrs:8080/image/download?url={}",
+    "{}/image/download?url={}",
+    Settings::get().pictrs_url,
     utf8_percent_encode(image_url, NON_ALPHANUMERIC) // TODO this might not be needed
   );