use lowercase letter for error message in getOciURI func

Signed-off-by: James Sheppard <jgsheppa@protonmail.com>

pkg/downloader/chart_downloader.go

@@ -156,7 +156,7 @@ func (c *ChartDownloader) getOciURI(ref, version string, u *url.URL) (*url.URL,
 			return nil, err
 		}
 		if len(tags) == 0 {
-			return nil, fmt.Errorf("Unable to locate any tags in provided repository: %s", ref)
+			return nil, fmt.Errorf("unable to locate any tags in provided repository: %s", ref)
 		}
 
 		// Determine if version provided