Keep parking_lot on the fork-safe core

On Unix when a multithreaded process forks after using a parking_lot lock, this upgrade routes those locks through registry parking_lot_core 0.10.0 (see the new Cargo.lock dependency), while ForkStopTheWorld::begin_child_repair() still invokes reinit_after_fork() on the separately patched 0.9.12 core used directly by rustpython-vm. The child therefore resets the wrong core's global parking queues and can inherit queue state or bucket locks owned by vanished parent threads, causing a later parking_lot operation to hang; the fork-safe core patch must be upgraded and used by parking_lot as part of this bump.

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