fix(future.py): add tests and fixes

[carlosmiei]

• with this edit all tests seem to work without any warnings thrown
• continues https://github.com/ccxt/ccxt/pull/22101/files

[carlosmiei]

If it test poloniexfutures I get different errors repeatedly...

e "/Users/cjg/Git/ccxt15/ccxt/python/ccxt/pro/poloniexfutures.py", line 751, in handle_l2_order_book
    self.handle_delta(orderBook, data)
  File "/Users/cjg/Git/ccxt15/ccxt/python/ccxt/pro/poloniexfutures.py", line 823, in handle_delta
    raise InvalidNonce(self.id + ' watchOrderBook received an out-of-order nonce')
ccxt.base.errors.InvalidNonce: poloniexfutures watchOrderBook received an out-of-order nonce

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/Users/cjg/Git/ccxt15/ccxt/python/ccxt/pro/test/base/test_close.py", line 73, in <module>
    run(test_close())
  File "/opt/homebrew/Cellar/python@3.11/3.11.7_1/Frameworks/Python.framework/Versions/3.11/lib/python3.11/asyncio/runners.py", line 190, in run
    return runner.run(main)
           ^^^^^^^^^^^^^^^^
  File "/opt/homebrew/Cellar/python@3.11/3.11.7_1/Frameworks/Python.framework/Versions/3.11/lib/python3.11/asyncio/runners.py", line 118, in run
    return self._loop.run_until_complete(task)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/homebrew/Cellar/python@3.11/3.11.7_1/Frameworks/Python.framework/Versions/3.11/lib/python3.11/asyncio/base_events.py", line 653, in run_until_complete
    return future.result()
           ^^^^^^^^^^^^^^^
  File "/Users/cjg/Git/ccxt15/ccxt/python/ccxt/pro/test/base/test_close.py", line 59, in test_close
    assert False
AssertionError
Task was destroyed but it is pending!
task: <Task pending name='Task-25' coro=<Throttler.looper() done, defined at /Users/cjg/Git/ccxt15/ccxt/python/ccxt/async_support/base/throttler.py:21> wait_for=<Future pending cb=[Task.task_wakeup()]>>
poloniexfutures requires to release all resources with an 

[pcriadoperez]

I tested with the latest changes from master and the poloniexfutures errors doesn't show up anymore