Latest GitHub Runner breaks DocFx build

[pkbullock]

I get a permissions error in the logs.

GitHub Actions runner Ubuntu-24.04 causes issues.

Reverting to the older running works, but this is only supported for a period of time maybe 2 years. DocFx needs to be rechecked and see if this is due to running an older version of DocFx.

Docs: actions/runner-images#10636

Ref fix: 262885b

This might be because I am using older .Net. Investigation needed.

[pkbullock]

Might be time to push hard for #511 and #726