Hide create openpgp key from card command for <2.3
When testing this with 2.2.31 it showed errors so better
not offer a button that only produces an error. According
to the GnuPG Maintainer this should work with 2.3
FWIW: I tested it with a freshly created card and thus keys. When hitting the "create OpenPGP Key " button, a warning was shown that a key already exists, I selected the do-anyway thing but the created keys had different fingerprints then. Thus the creation time was not taken in account. I recall that I implemented this for gpg-card and thus only for 2.3 - it is just quite likely that it does not work for 2.2.