PR: Pin xlrd to the 1.* serie

[jnsebgosselin]

Xlrd 2.x series does not support reading xlsx type files unlike the 1.x series.

see https://github.com/python-excel/xlrd:

This library will no longer read anything other than .xls files. For alternatives that read newer file formats, please see http://www.python-excel.org/.

We get an error when trying to read this type of file now, which is rather problematic. So we are going to pin xlrd to the 1.x series for the time being until we switch properly to another package to read xlsx files.