Build command make latexpdf (latexmk: Command not found)

[scottclowe]

The latex build action

    - name: Build PDF docs
      uses: ammaraskar/sphinx-action@master
      with:
        docs-folder: "docs/"
        pre-build-command: "apt-get update -y && apt-get install -y latexmk texlive-latex-recommended texlive-latex-extra texlive-fonts-recommended"
        build-command: "make latexpdf"

was previously running correctly, but has (today) started failing with the error:

make[1]: latexmk: Command not found

Here's links to the relevant files:

• Workflow file
• Broken run
• Last successful run

For the repo in question, no documentation changes or changes to the documentation workflow have occurred between the last successful run 6 days ago and the recent failing build. I note that no commits have been made to ammaraskar/sphinx-action in the past 6 days. And the sphinxdoc base docker image has not been changed.

I'm at a loss to understand what is causing this problem.