docs: change from detecting version to since tag (#13127)

* update everything from version to since

* update events

* regenerate oas

www/utils/generated/oas-output/operations/store/post_store_carts_[id]_customer.ts

@@ -97,7 +97,7 @@
  *       ```
  *     description: Emitted when the customer in the cart is transferred.
  *     deprecated: false
- *     version: 2.8.0
+ *     since: 2.8.0
  * 
 */
 

www/utils/generated/oas-output/operations/store/post_store_returns.ts

@@ -85,7 +85,7 @@
  *       ```
  *     description: Emitted when a return is marked as received.
  *     deprecated: false
- * x-version: 2.8.0
+ * x-since: 2.8.0
  * 
 */