fix: add elf2uf2-rs to Dockerfile to trigger GHCR image build

Agent-Logs-Url: https://github.com/Baker-link-Lab/bakerlink_tutorial_template/sessions/e422952a-6775-4491-9d29-321e4832c87b

Co-authored-by: Baker-Tanaka <42606588+Baker-Tanaka@users.noreply.github.com>

Author: Copilot

.docker/Dockerfile

@@ -5,3 +5,4 @@ RUN cargo install flip-link --version 0.1.10
 RUN rustup component add rustfmt
 RUN rustup component add llvm-tools
 RUN cargo install cargo-binutils
+RUN cargo install elf2uf2-rs --locked