Use and test the proper type for quantity and total_quantity in inventory counting

Since issue10413 assigned value has always the right type.

inventory.py

@@ -590,7 +590,7 @@ class Count(Wizard):
         values['product'] = line.product.id
         values['uom'] = line.uom.id
         if line.uom.rounding == 1:
-            values['quantity'] = 1
+            values['quantity'] = 1.
         return values
 
     def get_line_domain(self, inventory):

tests/scenario_stock_inventory_count.rst

@@ -83,9 +83,9 @@ Count inventory::
     ...     inventory.id, product.id)).save()
     >>> count.execute('quantity')
     >>> count.form.quantity
-    1
+    1.0
     >>> count.form.total_quantity
-    1
+    1.0
     >>> count.execute('add')
 
     >>> count.form.search = product