dockerfile: fix unpacking of containerd binaries
it turns out that within the tarball, everything sits under `bin/`,
thus, we were creating
/usr/local/concourse/bin/bin/containerd ...
by using `strip-components=1` we're able to remove that top-level `bin`
coming from the containerd tarball.
@@ -20,7 +20,7 @@ RUN apt update && apt install -y curl
RUN set -x && \
curl -sSL https://github.com/containerd/containerd/releases/download/v$CONTAINERD_VERSION/containerd-$CONTAINERD_VERSION.linux-amd64.tar.gz \
- | tar -zvxf - -C /usr/local/concourse/bin && \
+ | tar -zvxf - -C /usr/local/concourse/bin --strip-components=1 && \
curl -sSL https://github.com/opencontainers/runc/releases/download/$RUNC_VERSION/runc.amd64 \
-o /usr/local/concourse/bin/runc && chmod +x /usr/local/concourse/bin/runc && \
curl -sSL https://github.com/containernetworking/plugins/releases/download/$CNI_VERSION/cni-plugins-linux-amd64-$CNI_VERSION.tgz \
