test: logging: dictionary: fix build error

In `tests/subsys/logging/dictionary` we don't include stdio.h
header but use standard stream definitions (i.e. `stdout`)
which cause build issues (if the minimal libc is used).

Fix that.

Signed-off-by: Evgeniy Paltsev <PaltsevEvgeniy@gmail.com>
Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>