use errors pkg instead of github.com/pkg/errors

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

pkg/lint/rules/chartfile_test.go

@@ -17,13 +17,12 @@ limitations under the License.
 package rules
 
 import (
+	"errors"
 	"os"
 	"path/filepath"
 	"strings"
 	"testing"
 
-	"github.com/pkg/errors"
-
 	"helm.sh/helm/v3/pkg/chart"
 	"helm.sh/helm/v3/pkg/chartutil"
 	"helm.sh/helm/v3/pkg/lint/support"