[FIX] base_import : need xlrd to import excel

[fmdl]

Description of the issue/feature this PR addresses:
Need xlrd to import excel
Work on runbot, but not in local

Current behavior before PR:
Import preview failed due to: Unable to load "xlsx" file: requires Python module "xlrd >= 0.8".

Desired behavior after PR is merged:

--
I confirm I have signed the CLA and read the PR guidelines at www.odoo.com/submit-pr

[mart-e]

Hello,

I let @sle-odoo the final word but I don't think this is correct.
The requirements.txt is for the minimum packages for Odoo to work. If you do not have xlrd, Odoo will still work without crashing, it is just that some features will not be available, like the import of xlsx files.
Just install the xlrd package to make it work locally.

[fmdl]

I understand. Regards

[mart-e]

The "blocked" status does not mean "no", it is just that I needed info before merging it.
After discussion with @sle-odoo adding it in requirements.txt is actually fine. Seems that what I was saying is for the setup file, not requirements.

Merged at 0ac303d