python-gnupg: 0.3.8 -> 0.4.0 and disable tests

All 20 tests did fail because no gpg binary was found. With gnupg1 as
build input they never finish. Deactivating them might be the best
option for now (and it improves the current situation since they never
actually succeeded anyway -> build was failing, I noticed this while
running nox-review for #24390).