[FIX] survey: Unescape characters in mail subject

To reproduce the error:
Create a survey (title must contain ") and send it

Error:
The mail subject is incorrect: the character " is replaced with "

OPW-2536206

closes odoo/odoo#71363

X-original-commit: a2d46c2d
Signed-off-by: Nicolas Lempereur (nle) <nle@odoo.com>
Signed-off-by: Adrien Widart <adwid@users.noreply.github.com>