cos/tools: upgrade Go toolchain and builder images to 1.26.6 to resolve CVE-2026-33818 and CVE-2026-56865

Upgrade Go toolchain in go.mod, WORKSPACE, and all Go builder Dockerfiles
across cos/tools to Go 1.26.6 to resolve CVE-2026-33818 and CVE-2026-56865.

BUG=b/548593947
TEST=go build -mod=vendor ./src/cmd/cos_dkms/main.go
RELEASE_NOTE=None

Change-Id: I683f92dfd6bc26d34c5b159e01c264bdc1b92e12
Reviewed-on: https://cos-review.googlesource.com/c/cos/tools/+/187426
Tested-by: Chenglong Tang <chenglongtang@google.com>
Reviewed-by: Derek Taylor <ddtaylor@google.com>
Cloud-Build: 228075978874@cloudbuild.gserviceaccount.com <228075978874@cloudbuild.gserviceaccount.com>
10 files changed
tree: a581f33794e525eb23eaf3e7be3bd062b7f58dee
  1. coverage/
  2. release/
  3. src/
  4. testing/
  5. vendor/
  6. .bazelignore
  7. .gitignore
  8. BUILD.bazel
  9. cloudbuild.yaml
  10. CONTRIBUTING.md
  11. deps.bzl
  12. go.mod
  13. go.sum
  14. LICENSE
  15. postsubmit-cloudbuild.yaml
  16. README.md
  17. run_builds.sh
  18. run_unit_tests.sh
  19. WORKSPACE
README.md

Tools for Container-Optimized OS

This is a repository of various tools developed for Container-Optimized OS. Examples include cos-gpu-installer, cos-toolbox, etc.

See CONTRIBUTING.md for how to contribute.