[IMP] mail: change smiley
[IMP] mail: change smiley

Critical improvement, 
`:)` was making a laughing guy that could be considered as mockery.
This smiley is way more friendly and should improve support feedback by at
least an order of magnitude better, maybe two.

Closes #16672

ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo