[FIX] account: tax's widget error

- Create a new purchase tax with 0 as amount (Tax 0%);
- Create a new Bill, add a new line with the new Tax 0%;
- Use the tax's widget to modify the tax amount.

Before this commit, an error message was shown.

Now, only taxes values bigger than zero can be modified with the widget.

opw-2307761

X-original-commit: 03ee8036b3ea344372736beeefe6c4d74e4e62be

addons/account/static/src/xml/tax_group.xml

@@ -10,7 +10,7 @@
                             <label class="o_form_label" t-esc="line[0]"/>
                         </td>
                         <td class="oe_tax_group_editable" t-att-data-tax-group-id="line[6]">
-                            <t t-if="displayEditWidget">
+                            <t t-if="displayEditWidget and line[1] !== 0">
                                 <span class="tax_group_edit">
                                     <i class="fa fa-pencil"></i>
                                     <span class="oe_tax_group_amount_value">
@@ -21,7 +21,7 @@
                                     <input type="text" class="o_field_float o_field_number o_input" t-att-data-original-value="line[1]"/>
                                 </span>
                             </t>
-                            <t t-if="!displayEditWidget">
+                            <t t-if="!displayEditWidget or line[1] === 0">
                                 <span class="oe_tax_group_amount_value">
                                     <t t-esc="line[3]"/>
                                 </span>