[release-1.10] 🌱 Bump Go to v1.23.12

[mboersma]

What this PR does / why we need it:

Updates the Go toolchain to the latest patch release.

go1.23.12 (released 2025-08-06) includes security fixes to the database/sql and os/exec packages, as well as bug fixes to the runtime. See the Go 1.23.12 milestone on our issue tracker for details.

Which issue(s) this PR fixes:

N/A, but see #12531 for prior art.

/area dependency

[mboersma]

/cherry-pick release-1.9

[k8s-infra-cherrypick-robot]

@mboersma: once the present PR merges, I will cherry-pick it on top of release-1.9 in a new PR and assign it to you.

In response to this:

/cherry-pick release-1.9

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-sigs/prow repository.

[sbueringer]

Thx!

/lgtm
/approve

[k8s-ci-robot]

LGTM label has been added.

Git tree hash: 983f8d1a210b66f168e8059218c96f93f56d7815

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: sbueringer

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:

• OWNERS [sbueringer]

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

[k8s-infra-cherrypick-robot]

@mboersma: #12612 failed to apply on top of branch "release-1.9":

Applying: Bump Go to v1.23.12
Using index info to reconstruct a base tree...
M	Makefile
M	Tiltfile
M	netlify.toml
Falling back to patching base and 3-way merge...
Auto-merging netlify.toml
Auto-merging Tiltfile
Auto-merging Makefile
CONFLICT (content): Merge conflict in Makefile
error: Failed to merge in the changes.
hint: Use 'git am --show-current-patch=diff' to see the failed patch
hint: When you have resolved this problem, run "git am --continue".
hint: If you prefer to skip this patch, run "git am --skip" instead.
hint: To restore the original branch and stop patching, run "git am --abort".
hint: Disable this message with "git config advice.mergeConflict false"
Patch failed at 0001 Bump Go to v1.23.12

In response to this:

/cherry-pick release-1.9

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-sigs/prow repository.