chore: prepare Tokio v1.45.0 release

[carllerche]

Added

• metrics: stabilize worker_total_busy_duration, worker_park_count, and
  worker_unpark_count (#6899, #7276)
• process: add Command::spawn_with (#7249)

Changed

• io: do not require Unpin for some trait impls (#7204)
• rt: mark runtime::Handle as unwind safe (#7230)
• time: revert internal sharding implementation (#7226)

Unstable

• rt: remove alt multi-threaded runtime (#7275)

[Darksonn]

Thanks.