Bump golang from fd9306e to eb3f9ac in /integration (#1127)

Bumps golang from `fd9306e` to `eb3f9ac`.

---
updated-dependencies:
- dependency-name: golang
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

integration/Dockerfile

@@ -1,6 +1,6 @@
 # This Dockerfile builds a base image for the certificate-transparency-go CloudBuild integration testing.
 # See https://hub.docker.com/_/golang for the set of golang base images.
-FROM golang:buster@sha256:fd9306e1c664bd49a11d4a4a04e41303430e069e437d137876e9290a555e06fb as ct_testbase
+FROM golang:buster@sha256:eb3f9ac805435c1b2c965d63ce460988e1000058e1f67881324746362baf9572 as ct_testbase
 
 WORKDIR /testbase