do not use ioutil (#9206)

types/genesis.go

@@ -5,7 +5,7 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
-	"io/ioutil"
+	"os"
 	"time"
 
 	"github.com/tendermint/tendermint/crypto"
@@ -126,7 +126,7 @@ func GenesisDocFromJSON(jsonBlob []byte) (*GenesisDoc, error) {
 
 // GenesisDocFromFile reads JSON data from a file and unmarshalls it into a GenesisDoc.
 func GenesisDocFromFile(genDocFile string) (*GenesisDoc, error) {
-	jsonBlob, err := ioutil.ReadFile(genDocFile)
+	jsonBlob, err := os.ReadFile(genDocFile)
 	if err != nil {
 		return nil, fmt.Errorf("couldn't read GenesisDoc file: %w", err)
 	}

types/genesis_test.go

@@ -1,7 +1,6 @@
 package types
 
 import (
-	"io/ioutil"
 	"os"
 	"testing"
 
@@ -122,7 +121,7 @@ func TestGenesisGood(t *testing.T) {
 }
 
 func TestGenesisSaveAs(t *testing.T) {
-	tmpfile, err := ioutil.TempFile("", "genesis")
+	tmpfile, err := os.CreateTemp("", "genesis")
 	require.NoError(t, err)
 	defer os.Remove(tmpfile.Name())
 

types/part_set_test.go

@@ -1,7 +1,7 @@
 package types
 
 import (
-	"io/ioutil"
+	"io"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -57,7 +57,7 @@ func TestBasicPartSet(t *testing.T) {
 
 	// Reconstruct data, assert that they are equal.
 	data2Reader := partSet2.GetReader()
-	data2, err := ioutil.ReadAll(data2Reader)
+	data2, err := io.ReadAll(data2Reader)
 	require.NoError(t, err)
 
 	assert.Equal(t, data, data2)