Update api auth guard example to sanctum to avoid confusion (laravel#7264)

* Update `api` auth guard example to `sanctum` to avoid confusion

* Update http-tests.md

Co-authored-by: Taylor Otwell <[email protected]>

Author: crynobone

http-tests.md

@@ -173,7 +173,7 @@ Laravel's session is typically used to maintain state for the currently authenti
 
 You may also specify which guard should be used to authenticate the given user by passing the guard name as the second argument to the `actingAs` method:
 
-    $this->actingAs($user, 'api')
+    $this->actingAs($user, 'web')
 
 <a name="debugging-responses"></a>
 ### Debugging Responses