Replace deprecated ioutil usage (#2181)

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