Bump golang in /integration/cloudbuild/testbase

Bumps golang from `c2bc4ef` to `ef27a3c`.

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

Signed-off-by: dependabot[bot] <support@github.com>

integration/cloudbuild/testbase/Dockerfile

@@ -1,5 +1,5 @@
 # This Dockerfile builds a base image for Trillan integration tests.
-FROM golang:1.22.3-bookworm@sha256:c2bc4ef4064059a5dbd083e573dbd5d074858130fa3f1ed14807903b71ed99f1
+FROM golang:1.22.3-bookworm@sha256:ef27a3c07e6727d445fc70cd861f8f29f9152e51473ee3a952ea6bddd24ebf90
 
 WORKDIR /testbase