Error strings should not be capitalized

Reported by staticcheck 2022.1.2 (v0.3.2)

See: staticcheck.io

backend/qingstor/qingstor.go

@@ -253,7 +253,7 @@ func qsServiceConnection(ctx context.Context, opt *Options) (*qs.Service, error)
 		_protocol, _host, _port, err := qsParseEndpoint(endpoint)
 
 		if err != nil {
-			return nil, fmt.Errorf("The endpoint \"%s\" format error", endpoint)
+			return nil, fmt.Errorf("the endpoint \"%s\" format error", endpoint)
 		}
 
 		if _protocol != "" {

backend/qingstor/upload.go

@@ -184,7 +184,7 @@ func (u *uploader) upload() error {
 		fs.Debugf(u, "Uploading as single part object to QingStor")
 		return u.singlePartUpload(reader, u.readerPos)
 	} else if err != nil {
-		return fmt.Errorf("read upload data failed: %s", err)
+		return fmt.Errorf("read upload data failed: %w", err)
 	}
 
 	fs.Debugf(u, "Uploading as multi-part object to QingStor")