bug: (@vtmn/svelte): VtmnListItem component tabindex yields the value false

**Describe the bug**
In the VtmnListItem component the anchor tag has a parameter tabindex which is validating with the value of disabled. If the disabled is true the tabindex is -1 but if the disabled is false the value of the tabindex is false instead 0. Please do the necessary changes

tabindex={disabled && -1}
**Steps to reproduce**
We can reproduce this in all decathlon search pages wherever the list is displayed

**Expected behavior**

**Browsers affected**

**Version affected**