cos-gpu-installer: update nvidia-ctk to latest (1.18.1)

BUG=b/474231971
TEST=presubmit, build container and check `nvidia-ctk --version`

Change-Id: I880cab72cc0f6d6a8d3e54d099162d00beda744e
Reviewed-on: https://cos-review.googlesource.com/c/cos/tools/+/124646
Tested-by: Robert Kolchmeyer <rkolchmeyer@google.com>
Cloud-Build: GCB Service account <228075978874@cloudbuild.gserviceaccount.com>
Reviewed-by: Kevin Berry <kpberry@google.com>

src/cmd/cos_gpu_installer/Dockerfile

diff --git a/src/cmd/cos_gpu_installer/Dockerfile b/src/cmd/cos_gpu_installer/Dockerfile
index a8f00d8..59f9850 100644
--- a/src/cmd/cos_gpu_installer/Dockerfile
+++ b/src/cmd/cos_gpu_installer/Dockerfile
@@ -17,15 +17,12 @@
     libc6-dev pciutils gcc libelf-dev libssl-dev bison flex keyutils python3-minimal zlib1g-dev && \
     rm -rf /var/lib/apt/lists/*
 
-# TODO(kpberry) remove the version restriction after
-# https://github.com/NVIDIA/nvidia-container-toolkit/commit/d8e61f9f433fcefb5d2e9b626205bc0929552e41
-# is released. This bug only applies to version 1.18.0.
 RUN curl -fsSL https://nvidia.github.io/libnvidia-container/gpgkey | gpg \
     --dearmor -o /usr/share/keyrings/nvidia-container-toolkit-keyring.gpg && \
     curl -s -L https://nvidia.github.io/libnvidia-container/stable/deb/nvidia-container-toolkit.list \
     | sed 's#deb https://#deb [signed-by=/usr/share/keyrings/nvidia-container-toolkit-keyring.gpg] https://#g' \
     | tee /etc/apt/sources.list.d/nvidia-container-toolkit.list && apt-get update \
-    && apt-get install -y nvidia-container-toolkit=1.17.9-1 nvidia-container-toolkit-base=1.17.9-1
+    && apt-get install -y nvidia-container-toolkit nvidia-container-toolkit-base
 
 ENTRYPOINT ["/cos-gpu-installer"]
 CMD ["install"]