Update Dockerfile.triton.trt_llm_backend - apt-get update

Author: dmitry-tokarev-nv

dockerfile/Dockerfile.triton.trt_llm_backend

@@ -144,7 +144,8 @@ RUN git-lfs install \
     && git clone --single-branch --recurse-submodules --depth=1 -b ${TENSORRTLLM_REPO_TAG} ${TENSORRTLLM_REPO} tensorrt_llm
 
 RUN pip3 install --no-cache-dir polygraphy==0.49.9 mpi4py==3.1.5 cmake==4.0.3 ninja \
-    && apt-get install -y pkg-config  # needed for TRTLLM 
+    && apt-get update \
+    && apt-get install -y pkg-config
 ENV CMAKE_POLICY_VERSION_MINIMUM=3.5
 
 RUN cd tensorrt_llm && \