[11u] GHA checksums failure

[Langer, Christoph]

> yes, I recognized this as well. I missed this because my test went green:
> https://github.com/RealCLanger/jdk11u-dev/actions/runs/1099309576. But
> having a closer look now, it just worked because the Bootstrap JDK was
> restored from cache. I'll file a bug and update it.

Done. Fix is up for review: https://github.com/openjdk/jdk11u-dev/pull/203

Cheers
Christoph