(security) golang: bump Go version to 1.26.4-1

[bot-for-go]

Hi! 👋 I'm the Microsoft team's bot. This is an automated pull request I generated to bump the Go version to 1.26.4-1.

This update contains security fixes.

I'm not able to run the Azure Linux pipelines yet, so the Microsoft release runner will need to finalize this PR. @dagood

Finalization steps:

• Trigger Source Tarball Publishing with:
  Full Name:

  go1.26.4-20260602.8.src.tar.gz
  

  URL:

  https://github.com/microsoft/go/releases/download/v1.26.4-1/go1.26.4-20260602.8.src.tar.gz
  

• Trigger the Buddy Build with:
  First field:

  PR-17617
  

  Core spec:

  golang
  

• Post a PR comment with the URL of the triggered Buddy Build.
• Mark this draft PR as ready for review.

Thanks!

[dagood]

Buddy build queued: https://dev.azure.com/mariner-org/36d030d6-1d99-4ebd-878b-09af1f4f722f/_build/results?buildId=1132228

[mfrw]

LGTM :)
Thanks

[Kanishk-Bansal]

fixes a few CVEs mentioned at https://www.openwall.com/lists/oss-security/2026/06/03/2
We will merge this in dev branch, run through the nightly build and then fasttrack it.