chore(deps): replace deprecated ioutil with os and io in tests

[dandawg]

Description of your changes:

The ioutil package was deprecated in go 1.16 (see here). This PR replaces it's function calls with function calls from the os and io packages (as recommended).

Checklist:

• You have signed off your commits
• The title for your pull request (PR) should follow our title convention. Learn more about the pull request title convention used in this repository.

[google-oss-prow]

Hi @dandawg. Thanks for your PR.

I'm waiting for a kubeflow member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

I understand the commands that are listed here.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.

[dandawg]

/ok-to-test

[github-actions]

🚫 This command cannot be processed. Only organization members or owners can use the commands.

[google-oss-prow]

@dandawg: Cannot trigger testing until a trusted user reviews the PR and leaves an /ok-to-test message.

In response to this:

/ok-to-test

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.

[hbelmiro]

/lgtm
/ok-to-test

[google-oss-prow]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: hbelmiro

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• backend/OWNERS [hbelmiro]
• test/OWNERS [hbelmiro]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment