fix: Checkout repo before accessing file.

[cmaddox5]

Forgot to checkout the repo before access github.workspace.

[digitalcora]

The difficulty of testing workflows before they're merged strikes again 🙃

I wonder if we should add .github/** to the paths entries. Then for future modifications to (at least) the validation workflow, it can be tested on the branch before merging.

[cmaddox5]

Ooo, I like that idea. Will add to the validation step.

[digitalcora]

If we also add it to the upload step, that would ensure if we commit a change to the workflow, it will redo the upload (and in the process verify that the workflow is still valid and works). Of course, knowing about any problems there before merging an update to the workflow would be ideal... I guess we could also make that workflow executable on dispatch but maybe this is bikeshedding.