Fix broken blog deployment.
Fix broken blog deployment.

The deployment of blog posts has been broken for a while because apt-get install failed fetching some files because the repo metadata have been outdated.
davidzchen/bazel-blog,davidzchen/bazel-blog,davidzchen/bazel-blog,davidzchen/bazel-blog,bazelbuild/bazel-blog,bazelbuild/bazel-blog,bazelbuild/bazel-blog