[Bug] TensorDictMaxValueWriter raises error when no sample in a batch is accepted

[albertbou92]

Description

When TensorDictMaxValueWriter receives a batch of data via extend() but any sample if better than what the buffer contains, raises *** ValueError: not enough values to unpack (expected 2, got 0) when trying to obtain the insertion info keys, values = zip(*data_to_replace.items()) raises . This PR fixes this use case.

Motivation and Context

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You can use the syntax close #15213 if this solves the issue #15213

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[vmoens]

LGTM just a minor comment on the tests

[vmoens]

LGTM thanks a lot!