Migrate to assertEqual (element-hq#18488)

This small PR migrates from `unittest.assertEquals` to
`unittest.assertEqual` which is deprecated from Python2.7:
```python
DeprecationWarning: Please use assertEqual instead.
```

Signed-off-by: Emmanuel Ferdman <[email protected]>

Author: emmanuel-ferdman

tests/util/test_task_scheduler.py

@@ -112,11 +112,11 @@ def get_tasks_of_status(status: TaskStatus) -> List[ScheduledTask]:
 
         # At this point, there should be MAX_CONCURRENT_RUNNING_TASKS active tasks and
         # one scheduled task.
-        self.assertEquals(
+        self.assertEqual(
             len(get_tasks_of_status(TaskStatus.ACTIVE)),
             TaskScheduler.MAX_CONCURRENT_RUNNING_TASKS,
         )
-        self.assertEquals(
+        self.assertEqual(
             len(get_tasks_of_status(TaskStatus.SCHEDULED)),
             1,
         )
@@ -126,25 +126,25 @@ def get_tasks_of_status(status: TaskStatus) -> List[ScheduledTask]:
 
         # Check that MAX_CONCURRENT_RUNNING_TASKS tasks have run and that one
         # is still scheduled.
-        self.assertEquals(
+        self.assertEqual(
             len(get_tasks_of_status(TaskStatus.COMPLETE)),
             TaskScheduler.MAX_CONCURRENT_RUNNING_TASKS,
         )
         scheduled_tasks = get_tasks_of_status(TaskStatus.SCHEDULED)
-        self.assertEquals(len(scheduled_tasks), 1)
+        self.assertEqual(len(scheduled_tasks), 1)
 
         # The scheduled task should start 0.1s after the first of the active tasks
         # finishes
         self.reactor.advance(0.1)
-        self.assertEquals(len(get_tasks_of_status(TaskStatus.ACTIVE)), 1)
+        self.assertEqual(len(get_tasks_of_status(TaskStatus.ACTIVE)), 1)
 
         # ... and should finally complete after another second
         self.reactor.advance(1)
         prev_scheduled_task = self.get_success(
             self.task_scheduler.get_task(scheduled_tasks[0].id)
         )
         assert prev_scheduled_task is not None
-        self.assertEquals(
+        self.assertEqual(
             prev_scheduled_task.status,
             TaskStatus.COMPLETE,
         )