chore: remove refs to deprecated io/ioutil (#14485)

# Checklist for submitter

If some of the following don't apply, delete the relevant line.

- [ ] Changes file added for user-visible changes in `changes/` or
`orbit/changes/`.
See [Changes
files](https://fleetdm.com/docs/contributing/committing-changes#changes-files)
for more information.
- [ ] Documented any API changes (docs/Using-Fleet/REST-API.md or
docs/Contributing/API-for-contributors.md)
- [ ] Documented any permissions changes (docs/Using
Fleet/manage-access.md)
- [ ] Input data is properly validated, `SELECT *` is avoided, SQL
injection is prevented (using placeholders for values in statements)
- [ ] Added support on fleet's osquery simulator `cmd/osquery-perf` for
new osquery data ingestion features.
- [ ] Added/updated tests
- [ ] Manual QA for all new/changed functionality
  - For Orbit and Fleet Desktop changes:
- [ ] Manual QA must be performed in the three main OSs, macOS, Windows
and Linux.
- [ ] Auto-update manual QA, from released version of component to new
version (see [tools/tuf/test](../tools/tuf/test/README.md)).

Signed-off-by: guoguangwu <guoguangwu@magic-shield.com>

cmd/fleetctl/debug.go

@@ -8,7 +8,6 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
-	"io/ioutil"
 	"net"
 	"net/http"
 	"net/url"
@@ -57,7 +56,7 @@ func debugCommand() *cli.Command {
 }
 
 func writeFile(filename string, bytes []byte, mode os.FileMode) error {
-	if err := ioutil.WriteFile(filename, bytes, mode); err != nil {
+	if err := os.WriteFile(filename, bytes, mode); err != nil {
 		return err
 	}