Update Golang to 1.21.2

Makefile

@@ -16,13 +16,13 @@ local-build-static:
 
 # These only used for development. Release artifacts and docker images are produced by goreleaser.
 docker-test:
-	docker run -t -v $$PWD:/go/src/github.com/yannh/kubeconform -w /go/src/github.com/yannh/kubeconform golang:1.20 make local-test
+	docker run -t -v $$PWD:/go/src/github.com/yannh/kubeconform -w /go/src/github.com/yannh/kubeconform golang:1.21.2 make local-test
 
 docker-build:
-	docker run -t -v $$PWD:/go/src/github.com/yannh/kubeconform -w /go/src/github.com/yannh/kubeconform golang:1.20 make local-build
+	docker run -t -v $$PWD:/go/src/github.com/yannh/kubeconform -w /go/src/github.com/yannh/kubeconform golang:1.21.2 make local-build
 
 docker-build-static:
-	docker run -t -v $$PWD:/go/src/github.com/yannh/kubeconform -w /go/src/github.com/yannh/kubeconform golang:1.20 make local-build-static
+	docker run -t -v $$PWD:/go/src/github.com/yannh/kubeconform -w /go/src/github.com/yannh/kubeconform golang:1.21.2 make local-build-static
 
 build-bats:
 	docker build -t bats -f Dockerfile.bats .
@@ -32,11 +32,11 @@ docker-acceptance: build-bats
 	docker run --network none -t bats -p acceptance-nonetwork.bats
 
 goreleaser-build-static:
-	docker run -t -e GOOS=linux -e GOARCH=amd64 -v $$PWD:/go/src/github.com/yannh/kubeconform -w /go/src/github.com/yannh/kubeconform goreleaser/goreleaser:v1.20.0 build --single-target --skip-post-hooks --rm-dist --snapshot
+	docker run -t -e GOOS=linux -e GOARCH=amd64 -v $$PWD:/go/src/github.com/yannh/kubeconform -w /go/src/github.com/yannh/kubeconform goreleaser/goreleaser:v1.21.2 build --single-target --skip-post-hooks --rm-dist --snapshot
 	cp dist/kubeconform_linux_amd64_v1/kubeconform bin/
 
 release:
-	docker run -e GITHUB_TOKEN -e GIT_OWNER -t -v /var/run/docker.sock:/var/run/docker.sock -v $$PWD:/go/src/github.com/yannh/kubeconform -w /go/src/github.com/yannh/kubeconform goreleaser/goreleaser:v1.20.0 release --rm-dist
+	docker run -e GITHUB_TOKEN -e GIT_OWNER -t -v /var/run/docker.sock:/var/run/docker.sock -v $$PWD:/go/src/github.com/yannh/kubeconform -w /go/src/github.com/yannh/kubeconform goreleaser/goreleaser:v1.21.2 release --rm-dist
 
 update-deps:
 	go get -u ./...

go.mod

@@ -1,6 +1,6 @@
 module github.com/yannh/kubeconform
 
-go 1.20
+go 1.21.2
 
 require (
 	github.com/santhosh-tekuri/jsonschema/v5 v5.3.1

pkg/cache/ondisk.go

@@ -4,7 +4,7 @@ import (
 	"crypto/sha256"
 	"encoding/hex"
 	"fmt"
-	"io/ioutil"
+	"io"
 	"os"
 	"path"
 	"sync"
@@ -37,12 +37,12 @@ func (c *onDisk) Get(resourceKind, resourceAPIVersion, k8sVersion string) (inter
 		return nil, err
 	}
 
-	return ioutil.ReadAll(f)
+	return io.ReadAll(f)
 }
 
 // Set adds a JSON schema to the schema cache
 func (c *onDisk) Set(resourceKind, resourceAPIVersion, k8sVersion string, schema interface{}) error {
 	c.Lock()
 	defer c.Unlock()
-	return ioutil.WriteFile(cachePath(c.folder, resourceKind, resourceAPIVersion, k8sVersion), schema.([]byte), 0644)
+	return os.WriteFile(cachePath(c.folder, resourceKind, resourceAPIVersion, k8sVersion), schema.([]byte), 0644)
 }

pkg/registry/http.go

@@ -4,7 +4,7 @@ import (
 	"crypto/tls"
 	"errors"
 	"fmt"
-	"io/ioutil"
+	"io"
 	"log"
 	"net/http"
 	"os"
@@ -99,7 +99,7 @@ func (r SchemaRegistry) DownloadSchema(resourceKind, resourceAPIVersion, k8sVers
 		return url, nil, fmt.Errorf(msg)
 	}
 
-	body, err := ioutil.ReadAll(resp.Body)
+	body, err := io.ReadAll(resp.Body)
 	if err != nil {
 		msg := fmt.Sprintf("failed parsing schema from %s: %s", url, err)
 		if r.debug {

pkg/registry/http_test.go

@@ -3,7 +3,7 @@ package registry
 import (
 	"bytes"
 	"fmt"
-	"io/ioutil"
+	"io"
 	"net/http"
 	"strings"
 	"testing"
@@ -50,7 +50,7 @@ func TestDownloadSchema(t *testing.T) {
 			newMockHTTPGetter(func(url string) (resp *http.Response, err error) {
 				return &http.Response{
 					StatusCode: http.StatusNotFound,
-					Body:       ioutil.NopCloser(strings.NewReader("http response mock body")),
+					Body:       io.NopCloser(strings.NewReader("http response mock body")),
 				}, nil
 			}),
 			"http://kubernetesjson.dev",

pkg/registry/local.go

@@ -3,7 +3,7 @@ package registry
 import (
 	"errors"
 	"fmt"
-	"io/ioutil"
+	"io"
 	"log"
 	"os"
 )
@@ -47,7 +47,7 @@ func (r LocalRegistry) DownloadSchema(resourceKind, resourceAPIVersion, k8sVersi
 	}
 
 	defer f.Close()
-	content, err := ioutil.ReadAll(f)
+	content, err := io.ReadAll(f)
 	if err != nil {
 		msg := fmt.Sprintf("failed to read schema at %s: %s", schemaFile, err)
 		if r.debug {