Stop using deprecated ioutil functions

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))
 	}