golang: bump Go version to 1.26.8-1

[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 1.26.8-1.

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

Finalization steps:

• Trigger Source Tarball Publishing with:
  Full Name:

  go1.26.8-20260901.2.src.tar.gz
  

  URL:

  https://github.com/microsoft/go/releases/download/v1.26.8-1/go1.26.8-20260901.2.src.tar.gz
  

• Trigger the Buddy Build with:
  First field:

  PR-18693
  

  Core spec:

  golang-1.26
  

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

Thanks!

[azure-pipelines]

Azure Pipelines:
There may be pipelines that require an authorized user to comment /azp run to run.

[Davis Goodin (dagood)]

Buddy build queued: https://dev.azure.com/mariner-org/36d030d6-1d99-4ebd-878b-09af1f4f722f/_build/results?buildId=1195650