storageEngine ephemeralForTest is removed since MongoDB 7.0

[smeng9]

Describe the bug
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MongoDB 7.0 removes the storage engine, and the default settings no longer work.
We should treat versions >= 7 differently

To Reproduce
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1. Command list
2. See error

>>> from pymongo_inmemory import MongoClient
>>> m = MongoClient()

Expected behavior
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I expect my client can connect without a problem

Logs
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pymongo.errors.ServerSelectionTimeoutError: 127.0.0.1:27017: [Errno 61] Connection refused (configured timeouts: socketTimeoutMS: 20000.0ms, connectTimeoutMS: 20000.0ms), Timeout: 30s, Topology Description: <TopologyDescription id: 66f6ef8e519adcdf8ccb2bef, topology_type: Unknown, servers: [<ServerDescription ('127.0.0.1', 27017) server_type: Unknown, rtt: None, error=AutoReconnect('127.0.0.1:27017: [Errno 61] Connection refused (configured timeouts: socketTimeoutMS: 20000.0ms, connectTimeoutMS: 20000.0ms)')>]>

Screenshots
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Context:

• OS: macOS
• Version of pymongo_inmemory 0.4.2
• Version of mongo you are downloading 7.0
• Any other additional information about context