fix: use id instead of sku #39

Use entity_id in the WHERE clause instead of sku. This adjustment enhances the query's speed, especially when dealing with a large number of products.

During local testing, the export time decreased significantly from 50 minutes to just 8 minutes. Resulting in an increase in speed of 84%. This speed increase only seems to occur if you don't have all numbers as sku's.

README.md

@@ -7,8 +7,6 @@ Install package using composer
 composer require tweakwise/magento2-tweakwise-export
 ```
 
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 Enable module
 
 If 'Store Level Export' enabled single store feed  can be generated using the command line.