Add package workflow.

Signed-off-by: Jason Volk <jason@zemos.net>

docker/Dockerfile.cargo.install

@@ -22,9 +22,8 @@ WORKDIR /usr/src/tuwunel
 RUN \
 --mount=type=cache,dst=${RUSTUP_HOME},sharing=locked \
 --mount=type=cache,dst=${CARGO_HOME},sharing=locked \
---mount=type=cache,dst=${CARGO_TARGET_DIR},sharing=shared \
+--mount=type=cache,dst=${CARGO_TARGET_DIR},sharing=locked \
 <<EOF
-    env
     set -eux
     case "$cargo_profile" in
             "dev") profile_dir="debug";;
@@ -63,7 +62,6 @@ WORKDIR /
 RUN \
 --mount=type=bind,from=output,src=${install_temp},dst=/mnt/install \
 <<EOF
-    env
     set -eux
     cp -ndR --preserve=all -t ${CARGO_INSTALL_ROOT} /mnt/install/*
 EOF