Enable gocritic equalFold and fix issues (#34952)

Continuation of https://github.com/go-gitea/gitea/pull/34678.

---------

Signed-off-by: silverwind <me@silverwind.io>

modules/packages/pub/metadata.go

@@ -88,7 +88,7 @@ func ParsePackage(r io.Reader) (*Package, error) {
 			if err != nil {
 				return nil, err
 			}
-		} else if strings.ToLower(hd.Name) == "readme.md" {
+		} else if strings.EqualFold(hd.Name, "readme.md") {
 			data, err := io.ReadAll(tr)
 			if err != nil {
 				return nil, err