Versioned S3 buckets leak keys

[hannes-ucsc]

A left-over from #5551

$ python -Wall
Python 3.9.12 (main, Oct  8 2022, 00:52:50) 
[Clang 14.0.0 (clang-1400.0.29.102)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import gc
>>> from moto.s3.models import S3Backend
>>> s3 = S3Backend('us-west-1', '1234')
>>> s3.create_bucket('my-bucket','us-west-1')
<moto.s3.models.FakeBucket object at 0x104bb6520>
>>> s3.put_bucket_versioning('my-bucket', 'Enabled')
>>> s3.put_object('my-bucket','my-key', 'x')
<moto.s3.models.FakeKey object at 0x10340a1f0>
>>> s3.put_object('my-bucket','my-key', 'y')
<moto.s3.models.FakeKey object at 0x105c36970>
>>> s3.reset()
/Users/hannes/workspace/hca/azul/.venv/lib/python3.9/site-packages/moto/s3/models.py:347: ResourceWarning: S3 key was not disposed of in time
  warnings.warn("S3 key was not disposed of in time", ResourceWarning)
>>> gc.collect()
14311
>>> 

[bblommers]

Nice catch @hannes-ucsc