Bump go version to 1.20.8 to fix CVE

[tyuchn]

What type of PR is this?

Uncomment only one /kind <> line, hit enter to put that in a new line, and remove leading whitespaces from that line:

/kind api-change
/kind bug
/kind cleanup
/kind design
/kind documentation
/kind failing-test
/kind feature
/kind flake

What this PR does / why we need it:
bump go version to 1.20.8 to fix CVE-2023-39318, CVE-2023-39319
Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

N/A

[mattcary]

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: mattcary, tyuchn

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[tyuchn]

/retest

[sunnylovestiramisu]

/retest

[tyuchn]

@mattcary Per our offline discussion, may we force-merge this PR to mitigate the unhappiness of the FedRAMP SLA?

[tyuchn]

/cherry-pick release-1.9

[tyuchn]

/cherry-pick release-1.10

[tyuchn]

/cherry-pick release-1.11

[tyuchn]

/cherry-pick release-1.12

[k8s-infra-cherrypick-robot]

@tyuchn: new pull request created: #1392

In response to this:

/cherry-pick release-1.9

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[k8s-infra-cherrypick-robot]

@tyuchn: new pull request created: #1393

In response to this:

/cherry-pick release-1.10

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[k8s-infra-cherrypick-robot]

@tyuchn: new pull request created: #1394

In response to this:

/cherry-pick release-1.11

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[k8s-infra-cherrypick-robot]

@tyuchn: new pull request created: #1395

In response to this:

/cherry-pick release-1.12

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