cloud: fix %v in cases where we should use %w

Change-Id: I161fe87fbc2bf8c4c2c7756074fc1050f268121e
Reviewed-on: https://review.monogon.dev/c/monogon/+/3099
Tested-by: Jenkins CI
Reviewed-by: Lorenz Brun <lorenz@monogon.tech>
diff --git a/cloud/shepherd/mini/main.go b/cloud/shepherd/mini/main.go
index 0d7b11f..a5fb799 100644
--- a/cloud/shepherd/mini/main.go
+++ b/cloud/shepherd/mini/main.go
@@ -86,7 +86,7 @@
 	var r io.Reader
 	u, err := url.Parse(s)
 	if err != nil {
-		return nil, fmt.Errorf("failed parsing device list url: %v", err)
+		return nil, fmt.Errorf("failed parsing device list url: %w", err)
 	}
 
 	if u.Scheme != "file" {