lint: fix golangci-lint issues

[abhinav]

The following issues were fixed:

autogold.go:140:12: Error return value of `os.Remove` is not checked (errcheck)
autogold.go:7:2: 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)
expect.go:9:2: 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)

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