[FIX] packaging: include eml files in builds

The file addons/crm/test/customer_request.eml is used in
addons/crm/test/crm_lead_message.yml

Fixes #10750

MANIFEST.in

@@ -4,6 +4,7 @@ include README.md
 recursive-include openerp *.css
 recursive-include openerp *.csv
 recursive-include openerp *.doc
+recursive-include openerp *.eml
 recursive-include openerp *.gif
 recursive-include openerp *.html
 recursive-include openerp *.ico