Replace deprecated ioutil

Package `io/ioutil` was deprecated in golang 1.16, preventing podman from
building under Fedora 37.  Fortunately, functionality identical
replacements are provided by the packages `io` and `os`.  Replace all
usage of all `io/ioutil` symbols with appropriate substitutions
according to the golang docs.

Signed-off-by: Chris Evich <cevich@redhat.com>

pkg/api/server/handler_rid.go

@@ -2,7 +2,7 @@ package server
 
 import (
 	"fmt"
-	"io/ioutil"
+	"io"
 	"net/http"
 
 	"github.com/containers/podman/v4/pkg/api/types"
@@ -17,7 +17,7 @@ import (
 func referenceIDHandler() mux.MiddlewareFunc {
 	return func(h http.Handler) http.Handler {
 		// Only log Apache access_log-like entries at Info level or below
-		out := ioutil.Discard
+		out := io.Discard
 		if logrus.IsLevelEnabled(logrus.InfoLevel) {
 			out = logrus.StandardLogger().Out
 		}