print python_version_option for debug

Author: d-w-moore

irods/test/harness/build-docker.sh

@@ -31,6 +31,7 @@ for dockerfile in "${ARGS[@]}"; do
             PYTHON_VERSION="$temp"
         fi
         python_version_option=${PYTHON_VERSION:+"--build-arg=python_version=$PYTHON_VERSION"}
+        echo "************* DWM: python_version_option=[$python_version_option]"
     else
         package_version_option=""
     fi