use fmt and errors pkgs for lint files

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

pkg/lint/rules/template.go

@@ -205,7 +205,7 @@ func validateAllowedExtension(fileName string) error {
 		}
 	}
 
-	return errors.Errorf("file extension '%s' not valid. Valid extensions are .yaml, .yml, .tpl, or .txt", ext)
+	return fmt.Errorf("file extension '%s' not valid. Valid extensions are .yaml, .yml, .tpl, or .txt", ext)
 }
 
 func validateYamlContent(err error) error {

pkg/lint/rules/values.go

@@ -17,6 +17,7 @@ limitations under the License.
 package rules
 
 import (
+	"fmt"
 	"os"
 	"path/filepath"
 
@@ -54,7 +55,7 @@ func ValuesWithOverrides(linter *support.Linter, values map[string]interface{})
 func validateValuesFileExistence(valuesPath string) error {
 	_, err := os.Stat(valuesPath)
 	if err != nil {
-		return errors.Errorf("file does not exist")
+		return fmt.Errorf("file does not exist")
 	}
 	return nil
 }

pkg/lint/support/message_test.go

@@ -17,9 +17,8 @@ limitations under the License.
 package support
 
 import (
+	"errors"
 	"testing"
-
-	"github.com/pkg/errors"
 )
 
 var linter = Linter{}