fcitx5-keyman: Missing dependency on s390x

[Gunnar Hjalmarsson <gunnarhj@debian.org>]

Hello!

At Ubuntu they have just tried to rebuild the whole archive. When 
studying the result, I noticed a failed builddep for fcitx5-keyman on 
s390x: "Depends: libkmnkbp-dev but it is not installable"

Now that's not surprising, since libkmnkbp-dev is currently not built on 
s390x. From debian/changelog of keyman-keyboardprocessor:

Package: libkmnkbp-dev
Architecture: amd64 arm64 armel armhf i386 mipsel mips64el ppc64el riscv64

So maybe we should change "Architecture:" in fcitx5-keyman to reflect 
that (instead of "any").

--
Cheers,
Gunnar