fix: Rename the sortBy parameter option (#1647)

Renamed option for sortBy parameter from "lastRunStartedAt" to
"stats.lastRunStartedAt" to fit the
[TICKET](https://app.zenhub.com/workspaces/platform-team-5f6454160d9f82000fa6733f/issues/gh/apify/apify-core/20997)
specifications. Will merge when the [apify-core
PR](apify/apify-core#21731) is deployed

Author: protoss70

apify-api/openapi/paths/actors/acts.yaml

@@ -15,7 +15,7 @@ get:
     order, therefore you can use pagination to incrementally fetch all Actors while new
     ones are still being created. To sort the records in descending order, use the `desc=1` parameter.
 
-    You can also sort by `lastRunStartedAt` by using the `sortBy=lastRunStartedAt` query parameter.
+    You can also sort by your last run by using the `sortBy=stats.lastRunStartedAt` query parameter.
     In this case, descending order means the most recently run Actor appears first.
 
   operationId: acts_get
@@ -64,11 +64,11 @@ get:
     - name: sortBy
       in: query
       description: |
-        Field to sort the records by. The default is `createdAt`. You can also use `lastRunStartedAt` to sort
+        Field to sort the records by. The default is `createdAt`. You can also use `stats.lastRunStartedAt` to sort
         by the most recently ran Actors.
       schema:
         type: string
-        enum: [createdAt, lastRunStartedAt]
+        enum: [createdAt, stats.lastRunStartedAt]
         example: createdAt
   responses:
     '200':