remove deprecated use of ioutil (#5205)

Signed-off-by: Jörn Friedrich Dreyer <jfd@butonic.de>

Signed-off-by: Jörn Friedrich Dreyer <jfd@butonic.de>

services/proxy/pkg/middleware/authentication.go

@@ -3,7 +3,6 @@ package middleware
 import (
 	"fmt"
 	"io"
-	"io/ioutil"
 	"net/http"
 	"regexp"
 	"strings"
@@ -113,7 +112,7 @@ func Authentication(auths []Authenticator, opts ...Option) func(next http.Handle
 				// https://github.com/golang/go/issues/15527
 
 				defer r.Body.Close()
-				_, _ = io.Copy(ioutil.Discard, r.Body)
+				_, _ = io.Copy(io.Discard, r.Body)
 			}
 		})
 	}

services/proxy/pkg/middleware/oidc_auth.go

@@ -3,7 +3,7 @@ package middleware
 import (
 	"context"
 	"encoding/json"
-	"io/ioutil"
+	"io"
 	"net/http"
 	"strings"
 	"sync"
@@ -181,7 +181,7 @@ func (m *OIDCAuthenticator) getKeyfunc() *keyfunc.JWKS {
 		}
 		defer resp.Body.Close()
 
-		body, err := ioutil.ReadAll(resp.Body)
+		body, err := io.ReadAll(resp.Body)
 		if err != nil {
 			m.Logger.Error().Err(err).Msg("unable to read discovery response body")
 			return nil