Fix #7997

[jindaxia]

Fix #7997

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Description

In the redis Sentinel class ，if sentinel_kwargs is None, it use 'socket_' in connection_kwargs as the sentinel_kwargs,

    def __init__(
        self,
        sentinels,
        min_other_sentinels=0,
        sentinel_kwargs=None,
        **connection_kwargs,
    ):
        # if sentinel_kwargs isn't defined, use the socket_* options from
        # connection_kwargs
        if sentinel_kwargs is None:
            sentinel_kwargs = {
                k: v for k, v in connection_kwargs.items() if k.startswith("socket_")
            }
        self.sentinel_kwargs = sentinel_kwargs

        self.sentinels = [
            Redis(hostname, port, **self.sentinel_kwargs)
            for hostname, port in sentinels
        ]
        self.min_other_sentinels = min_other_sentinels
        self.connection_kwargs = connection_kwargs

but sentinel_kwargs = self._transport_options.get("sentinel_kwargs", {}) use a empty dict as the default value,
{} is not None,

[auvipy]

I would expect a failing testcase here as well to verify it