message: Add a sha256 digest to the image of Docker to specify the version.
diff: @@ -13,7 +13,7 @@ jobs:
  - run: |
  npm ci
  npm run compile
  - docker pull tianon/latex
  + docker pull tianon/latex@sha256:d9d5378ae77df3352aba36f9672a4c2d5c82861475508a1fae46b40369ed6ac9
  - name: Run tests
  uses: GabrielBB/xvfb-action@v1.0
  with:
  