ugh, now it says I can't even have a step using both 'users' and 'run' at all

  a step cannot have both the `uses` and `run` keys

Let's try defining the docker container for this step as 'container'?

Author: maltfield

.github/workflows/build.yml

@@ -23,7 +23,7 @@ jobs:
       shell: bash
 
     - name: Execute script to build linux AppImage
-      uses: docker://debian:buster-slim
+      container: debian:buster-slim
       run: "build/linux/buildAppImage.sh"
       shell: bash