feat: go 1.22 and slog migration (#557)

This change adds Go 1.22 as a build target and drops support for Go 1.20 and older. The golang.org/x/exp/slog import is migrated to log/slog.

Slog has been part of the Go standard library since Go 1.21. Therefore we are dropping support for older Go versions. This is in line of our support policy of "the latest two Go versions".

pkg/op/auth_request.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"log/slog"
 	"net"
 	"net/http"
 	"net/url"
@@ -14,7 +15,6 @@ import (
 	httphelper "github.com/zitadel/oidc/v3/pkg/http"
 	"github.com/zitadel/oidc/v3/pkg/oidc"
 	str "github.com/zitadel/oidc/v3/pkg/strings"
-	"golang.org/x/exp/slog"
 )
 
 type AuthRequest interface {

pkg/op/auth_request_test.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"errors"
 	"io"
+	"log/slog"
 	"net/http"
 	"net/http/httptest"
 	"net/url"
@@ -20,7 +21,6 @@ import (
 	"github.com/zitadel/oidc/v3/pkg/op"
 	"github.com/zitadel/oidc/v3/pkg/op/mock"
 	"github.com/zitadel/schema"
-	"golang.org/x/exp/slog"
 )
 
 func TestAuthorize(t *testing.T) {

pkg/op/error.go

@@ -4,11 +4,11 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"log/slog"
 	"net/http"
 
 	httphelper "github.com/zitadel/oidc/v3/pkg/http"
 	"github.com/zitadel/oidc/v3/pkg/oidc"
-	"golang.org/x/exp/slog"
 )
 
 type ErrAuthRequest interface {

pkg/op/error_test.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"fmt"
 	"io"
+	"log/slog"
 	"net/http"
 	"net/http/httptest"
 	"net/url"
@@ -14,7 +15,6 @@ import (
 	"github.com/stretchr/testify/require"
 	"github.com/zitadel/oidc/v3/pkg/oidc"
 	"github.com/zitadel/schema"
-	"golang.org/x/exp/slog"
 )
 
 func TestAuthRequestError(t *testing.T) {

pkg/op/mock/authorizer.mock.go

@@ -6,12 +6,12 @@ package mock
 
 import (
 	context "context"
+	slog "log/slog"
 	reflect "reflect"
 
 	gomock "github.com/golang/mock/gomock"
 	http "github.com/zitadel/oidc/v3/pkg/http"
 	op "github.com/zitadel/oidc/v3/pkg/op"
-	slog "golang.org/x/exp/slog"
 )
 
 // MockAuthorizer is a mock of Authorizer interface.

pkg/op/op.go

@@ -3,6 +3,7 @@ package op
 import (
 	"context"
 	"fmt"
+	"log/slog"
 	"net/http"
 	"time"
 
@@ -12,7 +13,6 @@ import (
 	"github.com/zitadel/schema"
 	"go.opentelemetry.io/otel"
 	"go.opentelemetry.io/otel/trace"
-	"golang.org/x/exp/slog"
 	"golang.org/x/text/language"
 
 	httphelper "github.com/zitadel/oidc/v3/pkg/http"
@@ -114,8 +114,6 @@ type OpenIDProvider interface {
 	Crypto() Crypto
 	DefaultLogoutRedirectURI() string
 	Probes() []ProbesFn
-
-	// EXPERIMENTAL: Will change to log/slog import after we drop support for Go 1.20
 	Logger() *slog.Logger
 
 	// Deprecated: Provider now implements http.Handler directly.
@@ -646,8 +644,6 @@ func WithCORSOptions(opts *cors.Options) Option {
 }
 
 // WithLogger lets a logger other than slog.Default().
-//
-// EXPERIMENTAL: Will change to log/slog import after we drop support for Go 1.20
 func WithLogger(logger *slog.Logger) Option {
 	return func(o *Provider) error {
 		o.logger = logger

pkg/op/server_http.go

@@ -2,6 +2,7 @@ package op
 
 import (
 	"context"
+	"log/slog"
 	"net/http"
 	"net/url"
 
@@ -11,7 +12,6 @@ import (
 	httphelper "github.com/zitadel/oidc/v3/pkg/http"
 	"github.com/zitadel/oidc/v3/pkg/oidc"
 	"github.com/zitadel/schema"
-	"golang.org/x/exp/slog"
 )
 
 // RegisterServer registers an implementation of Server.

pkg/op/server_http_test.go

@@ -5,6 +5,7 @@ import (
 	"context"
 	"fmt"
 	"io"
+	"log/slog"
 	"net/http"
 	"net/http/httptest"
 	"net/url"
@@ -19,7 +20,6 @@ import (
 	httphelper "github.com/zitadel/oidc/v3/pkg/http"
 	"github.com/zitadel/oidc/v3/pkg/oidc"
 	"github.com/zitadel/schema"
-	"golang.org/x/exp/slog"
 )
 
 func TestRegisterServer(t *testing.T) {

pkg/op/session.go

@@ -3,13 +3,13 @@ package op
 import (
 	"context"
 	"errors"
+	"log/slog"
 	"net/http"
 	"net/url"
 	"path"
 
 	httphelper "github.com/zitadel/oidc/v3/pkg/http"
 	"github.com/zitadel/oidc/v3/pkg/oidc"
-	"golang.org/x/exp/slog"
 )
 
 type SessionEnder interface {

pkg/op/token_request.go

@@ -2,12 +2,12 @@ package op
 
 import (
 	"context"
+	"log/slog"
 	"net/http"
 	"net/url"
 
 	httphelper "github.com/zitadel/oidc/v3/pkg/http"
 	"github.com/zitadel/oidc/v3/pkg/oidc"
-	"golang.org/x/exp/slog"
 )
 
 type Exchanger interface {