Unbreak CI image build (tensorflow 2.6.5, ci_gpu bugfix) (#11546)

* Pin protobuf to 3.20.1 due to #11545.

* Unpin and instead update to 2.6.5

* attempt to fix gpu build

* Revert to 2.6.3, pin protobuf for ci-arm.

* escape bash char

Author: areusch

docker/Dockerfile.ci_gpu

@@ -24,7 +24,7 @@ FROM nvidia/cuda:11.0.3-cudnn8-devel-ubuntu18.04
 RUN apt-key adv --fetch-keys https://developer.download.nvidia.com/compute/cuda/repos/ubuntu1804/x86_64/3bf863cc.pub
 
 # Base scripts
-RUN rm /etc/apt/sources.list.d/nvidia-ml.list && apt-get clean
+RUN rm -f /etc/apt/sources.list.d/nvidia-ml.list && apt-get clean
 RUN apt-get update --fix-missing
 
 COPY install/ubuntu_install_core.sh /install/ubuntu_install_core.sh

docker/install/ubuntu_install_tensorflow.sh

@@ -23,4 +23,4 @@ set -o pipefail
 pip3 install \
     "h5py==3.1.0" \
     keras==2.6 \
-    tensorflow==2.6.2
+    tensorflow==2.6.5

docker/install/ubuntu_install_tensorflow_aarch64.sh

@@ -26,5 +26,6 @@ apt-get install -y --no-install-recommends libhdf5-dev
 pip3 install \
     "h5py==3.1.0" \
     keras==2.6 \
-    tensorflow-aarch64==2.6.2 \
+    tensorflow-aarch64==2.6.3 \
+    "protobuf<4" \
     -f https://snapshots.linaro.org/ldcg/python-cache/tensorflow-aarch64/