tests/docker: move riscv64 cross container from sid to trixie

Although riscv64 isn't going to be a release architecture for trixie
the packages are still built while it is testing. Moving from sid will
also avoid some of the volatility we get from tracking the bleeding
edge.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20250108121054.1126164-26-alex.bennee@linaro.org>
2 files changed