Add PIP_ONLY_BINARY to Dockerfile (#596)

Signed-off-by: Ian Hoang <hoangia@amazon.com>
Co-authored-by: Ian Hoang <hoangia@amazon.com>

docker/Dockerfile

@@ -15,6 +15,7 @@ RUN apt-get -y update && \
 RUN groupadd --gid 1000 opensearch-benchmark && \
     useradd -d /opensearch-benchmark -m -k /dev/null -g 1000 -N -u 1000 -l -s /bin/bash benchmark
 
+ENV PIP_ONLY_BINARY=h5py
 RUN if [ -z "$VERSION" ] ; then python3 -m pip install opensearch-benchmark ; else python3 -m pip install opensearch-benchmark==$VERSION ; fi
 
 WORKDIR /opensearch-benchmark