go: removed io/ioutil

Since the minimum required version of Go has been bumped to 1.16, the
deprecation of io/ioutil can now be acted upon. This Commit removes the
remaining dependencies on ioutil and replaces them with their io or os
counterparts.

Signed-off-by: Moritz Poldrack <git@moritz.sh>
Acked-by: Robin Jarry <robin@jarry.cc>

commands/account/recover.go

@@ -3,7 +3,7 @@ package account
 import (
 	"bytes"
 	"errors"
-	"io/ioutil"
+	"io"
 	"os"
 	"path/filepath"
 
@@ -89,7 +89,7 @@ func (Recover) Execute(aerc *widgets.Aerc, args []string) error {
 			return nil, err
 		}
 		defer recoverFile.Close()
-		data, err := ioutil.ReadAll(recoverFile)
+		data, err := io.ReadAll(recoverFile)
 		if err != nil {
 			return nil, err
 		}

commands/msg/forward.go

@@ -6,7 +6,6 @@ import (
 	"errors"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"math/rand"
 	"os"
 	"path"
@@ -124,7 +123,7 @@ func (forward) Execute(aerc *widgets.Aerc, args []string) error {
 	}
 
 	if attachFull {
-		tmpDir, err := ioutil.TempDir("", "aerc-tmp-attachment")
+		tmpDir, err := os.MkdirTemp("", "aerc-tmp-attachment")
 		if err != nil {
 			return err
 		}

commands/msgview/open.go

@@ -3,7 +3,6 @@ package msgview
 import (
 	"fmt"
 	"io"
-	"io/ioutil"
 	"mime"
 	"os"
 	"time"
@@ -60,7 +59,7 @@ func (Open) Execute(aerc *widgets.Aerc, args []string) error {
 			}
 		}
 
-		tmpFile, err := ioutil.TempFile(os.TempDir(), "aerc-*"+extension)
+		tmpFile, err := os.CreateTemp(os.TempDir(), "aerc-*"+extension)
 		if err != nil {
 			aerc.PushError(err.Error())
 			return