refactor: replace deprecated ioutil with io and os (#423)

Co-authored-by: Patrik <zepatrik@users.noreply.github.com>

dockertest.go

@@ -6,7 +6,6 @@ package dockertest
 import (
 	"fmt"
 	"io"
-	"io/ioutil"
 	"net"
 	"os"
 	"path/filepath"
@@ -340,7 +339,7 @@ func (d *Pool) BuildAndRunWithBuildOptions(buildOpts *BuildOptions, runOpts *Run
 	err := d.Client.BuildImage(dc.BuildImageOptions{
 		Name:         runOpts.Name,
 		Dockerfile:   buildOpts.Dockerfile,
-		OutputStream: ioutil.Discard,
+		OutputStream: io.Discard,
 		ContextDir:   buildOpts.ContextDir,
 		BuildArgs:    buildOpts.BuildArgs,
 		Platform:     buildOpts.Platform,

dockertest_test.go

@@ -7,7 +7,6 @@ import (
 	"bytes"
 	"database/sql"
 	"fmt"
-	"io/ioutil"
 	"log"
 	"net/http"
 	"os"
@@ -199,11 +198,10 @@ func TestContainerWithPortBinding(t *testing.T) {
 
 func TestBuildImage(t *testing.T) {
 	// Create Dockerfile in temp dir
-	dir, _ := ioutil.TempDir("", "dockertest")
-	defer os.RemoveAll(dir)
+	dir := t.TempDir()
 
 	dockerfilePath := dir + "/Dockerfile"
-	ioutil.WriteFile(dockerfilePath,
+	os.WriteFile(dockerfilePath,
 		[]byte("FROM postgres:9.5"),
 		0o644,
 	)
@@ -217,11 +215,10 @@ func TestBuildImage(t *testing.T) {
 
 func TestBuildImageWithBuildArg(t *testing.T) {
 	// Create Dockerfile in temp dir
-	dir, _ := ioutil.TempDir("", "dockertest")
-	defer os.RemoveAll(dir)
+	dir := t.TempDir()
 
 	dockerfilePath := dir + "/Dockerfile"
-	ioutil.WriteFile(dockerfilePath,
+	os.WriteFile(dockerfilePath,
 		[]byte((`FROM busybox
 ARG foo
 RUN echo -n $foo > /build-time-value

examples/FakeGoogleCloudStorage.md

@@ -18,7 +18,7 @@ package main
 import (
 	"context"
 	"fmt"
-	"io/ioutil"
+	"io"
 	"net/http"
 	"os"
 	"strings"
@@ -198,7 +198,7 @@ func readFile(client *storage.Client, bucketName, fileName string) ([]byte, erro
 		return nil, err
 	}
 	defer reader.Close()
-	return ioutil.ReadAll(reader)
+	return io.ReadAll(reader)
 }
 
 func deleteFile(client *storage.Client, bucketName, fileName string) error {