[CI] Pin h5py version to < 3.0 to workaround issues with TF/Keras (#6808

)

* Pin h5py to use the previous major release (2.x) and not
   new version 3.0, due to incompatibilities with TF and Keras
   that make TVMC and Frontend tests to fail

docker/install/ubuntu_install_tensorflow.sh

@@ -20,4 +20,7 @@ set -e
 set -u
 set -o pipefail
 
-pip3 install tensorflow==2.3.1 keras==2.4.3 h5py
+# h5py is pinned to minor than 3 due to issues with
+# tensorflow:
+# https://github.com/tensorflow/tensorflow/issues/44467
+pip3 install tensorflow==2.3.1 keras==2.3.1 "h5py<3.0"