storage_stats: Actually check the HTTP status code

By default reqwest does not return an actual error for non-success HTTP
status codes like HTTP 404.

This lead to parser failures when trying to read the HTML error message
from a 404 reply as a deb822 document.

Use `Response::error_for_status()` to actually check for successful
status codes.

Signed-off-by: Emanuele Aina <emanuele.aina@collabora.com>

storage_stats/src/client.rs

@@ -60,7 +60,7 @@ impl Client {
     #[instrument(skip(self))]
     pub async fn get<U: IntoUrl + Clone + Debug>(&self, url: U) -> Result<Bytes> {
         let result = retry(ExponentialBackoff::default(), || async {
-            self.get_no_retry(url.clone()).await.map_err(|err| {
+            self.get_no_retry(url.clone()).await.error_for_status().map_err(|err| {
                 // Don't treat 404s as transient (because they're usually not + it can be
                 // handled in a higher layer to find the first file available).
                 if is_error_404(&err) {