Stop using deprecated ioutil functions

plugin/builtin/helmchartinflationgenerator/HelmChartInflationGenerator.go

@@ -10,7 +10,6 @@ package main
 import (
 	"bytes"
 	"fmt"
-	"io/ioutil"
 	"os"
 	"os/exec"
 	"path/filepath"
@@ -78,7 +77,7 @@ func (p *HelmChartInflationGeneratorPlugin) establishTmpDir() (err error) {
 		// already done.
 		return nil
 	}
-	p.tmpDir, err = ioutil.TempDir("", "kustomize-helm-")
+	p.tmpDir, err = os.MkdirTemp("", "kustomize-helm-")
 	return err
 }
 
@@ -216,7 +215,7 @@ func (p *HelmChartInflationGeneratorPlugin) writeValuesBytes(
 		return "", fmt.Errorf("cannot create tmp dir to write helm values")
 	}
 	path := filepath.Join(p.tmpDir, p.Name+"-kustomize-values.yaml")
-	return path, ioutil.WriteFile(path, b, 0644)
+	return path, os.WriteFile(path, b, 0644)
 }
 
 func (p *HelmChartInflationGeneratorPlugin) cleanup() {

plugin/builtin/helmchartinflationgenerator/HelmChartInflationGenerator_test.go

@@ -5,7 +5,7 @@ package main_test
 
 import (
 	"fmt"
-	"io/ioutil"
+	"os"
 	"path/filepath"
 	"testing"
 
@@ -473,7 +473,7 @@ func TestHelmChartInflationGeneratorWithIncludeCRDs(t *testing.T) {
 
 	// we store this data outside of the _test.go file as its sort of huge
 	// and has backticks, which makes string literals wonky
-	testData, err := ioutil.ReadFile("include_crds_testdata.txt")
+	testData, err := os.ReadFile("include_crds_testdata.txt")
 	if err != nil {
 		t.Error(fmt.Errorf("unable to read test data for includeCRDs: %w", err))
 	}