chore(deps): bump golang from 8305f5f to d709837 in /.buildkite

Bumps golang from `8305f5f` to `d709837`.

---
updated-dependencies:
- dependency-name: golang
  dependency-version: 1.25.1
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

.buildkite/Dockerfile.build

@@ -1,4 +1,4 @@
-FROM golang:1.25.1@sha256:8305f5fa8ea63c7b5bc85bd223ccc62941f852318ebfbd22f53bbd0b358c07e1
+FROM golang:1.25.1@sha256:d7098379b7da665ab25b99795465ec320b1ca9d4addb9f77409c4827dc904211
 
 COPY --from=goreleaser/goreleaser-pro:v2.9.0@sha256:adf70d3f53233855f6091c58c2e3f182fd41311fe322cbf3284994bb6991a53d /usr/bin/goreleaser /usr/local/bin/goreleaser
 COPY --from=ghcr.io/ko-build/ko:20b15e67194215721faba356b857fcf5d621dfaa /ko-app/ko /usr/local/bin/ko