revert: "chore: mark "Add a price by a catalog" as unstable"

This reverts commit f7b2a13.

This didn't work as I put a tag on a keyword rather than on a test case.

Relate to #1452

Author: php-coder

Diff for: src/test/robotframework/series/add-price/logic.robot

@@ -24,7 +24,6 @@ Before Test Suite
 	Go To                               ${SITE_URL}/series/4
 
 Add a price
-	[Tags]                            unstable
 	[Arguments]                       ${catalog}  ${price}  ${currency}
 	Select From List By Value         id:price-catalog-name  ${catalog}
 	Input Text                        id:catalog-price  ${price}