fix(linux): Fix libkeymancore-dev dependencies

This change adds `libicu-dev` as a dependency for `libkeymancore-dev`.
While it is possible to dynamically build without ICU it is required
when doing a static build.

Closes #10864 and [Debian bug #1064915](
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1064915).