update match-case to if/else for backward compatibility for Python ve…

[2020ayao]

…rsions < 3.10

What this PR does / why we need it:

Which issue(s) this PR fixes (optional, in Fixes #<issue number>, #<issue number>, ... format, will close the issue(s) when PR gets merged):
Fixes #

Checklist:

• Docs included if any changes are user facing

[google-cla]

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View this failed invocation of the CLA check for more information.

For the most up to date status, view the checks section at the bottom of the pull request.

[google-oss-prow]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: 2020ayao
Once this PR has been reviewed and has the lgtm label, please assign jinchihe for approval. For more information see the Kubernetes Code Review Process.

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

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[coveralls]

Pull Request Test Coverage Report for Build 8932153173

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 35.431%

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Totals
Change from base Build 8854426275:	0.0%
Covered Lines:	4380
Relevant Lines:	12362

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💛 - Coveralls

[tenzen-y]

@2020ayao Thank you for creating this PR.
Could you sign the DCO and cla in the following?

• https://github.com/kubeflow/training-operator/pull/2099/checks?check_run_id=24535517365
• https://github.com/kubeflow/training-operator/pull/2099/checks?check_run_id=24535517401

[tenzen-y]

ping @2020ayao

[andreyvelich]

Thank you for your PR @2020ayao!
Let's discuss it in this issue: #2096 (comment)
/hold