Replace deprecated ioutil usage

[nirs]

Fixing golangci-lint errors[1]:

Error: SA1019: "io/ioutil" has been deprecated since Go 1.19: As of
Go 1.16, the same functionality is now provided by package [io] or
package [os], and those implementations should be preferred in new
code. See the specific function documentation for details.
(staticcheck)

[1] https://github.com/spf13/cobra/actions/runs/10535452454/job/29194442289?pr=2180

[marckhouzam]

Thanks!