Bump go-version to 1.21.9 for release-3.5 due to CVE-2023-45288

[henrybear327]

Reference:

• PR Address CVE-2023-45288 #17703

Please read https://github.com/etcd-io/etcd/blob/main/CONTRIBUTING.md#contribution-flow.

[k8s-ci-robot]

Hi @henrybear327. Thanks for your PR.

I'm waiting for a etcd-io 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.

[ahrtr]

Question: why bump golang.org/x/net to v0.23.0 in the second commit? Did you see any issue if not bumping it?

[henrybear327]

Sorry for not being clear on this second commit.

The vulnerability scan on CI will report an error, thus, I decided to upgrade to the version specified up there.

Log extract:

go: downloading golang.org/x/vuln v1.0.4
go: downloading golang.org/x/mod v0.14.0
go: downloading golang.org/x/tools v0.1[7](https://github.com/etcd-io/etcd/actions/runs/8551422689/job/23430401128#step:6:8).0
go: downloading golang.org/x/sync v0.6.0
Scanning your code and 504 packages across 77 dependent modules for known vulnerabilities...

=== Symbol Results ===

Vulnerability #1: GO-2024-26[8](https://github.com/etcd-io/etcd/actions/runs/8551422689/job/23430401128#step:6:9)7
    HTTP/2 CONTINUATION flood in net/http
  More info: https://pkg.go.dev/vuln/GO-2024-2687
  Module: golang.org/x/net
    Found in: golang.org/x/net@v0.22.0
    Fixed in: golang.org/x/net@v0.23.0

[ahrtr]

Thanks for the clarification.

[ahrtr]

lgtm

Thanks.