[FIX] web: test breaking in newer Chrome due to rounding issue

Since (at least) Chrome 94+, some element's sizing computation returns a
slightly different value (in the order of a fraction of a pixel). Sadly,
due to rounding, this difference has an impact on exact sizing assertion
(specifically in the list view column sizing tests).

As the difference is *really* small, introducing a margin of error (i.e.
<= 1px) looks reasonnable ; as implemented in this commit.

closes odoo/odoo#92089

Forward-port-of: odoo/odoo#92066
Signed-off-by: Aaron Bohy (aab) <aab@odoo.com>
Signed-off-by: Pierre Paridans (app) <app@odoo.com>