submodule: bump openthread from `54afce9` to `4e8f3c0`

[dependabot[bot]]

Bumps openthread from 54afce9 to 4e8f3c0.

Commits

• 4e8f3c0 [posix] check whether the RCP support specified Spinel properties (#10387)
• fc0646c [simulation] fix tiny issue of infra if (#10402)
• a46786b [cli] udp bind doc update to clarify that multicast address cannot be used ...
• fad66e2 [posix] add OT sys API to get the spinel driver (#10393)
• See full diff in compare view

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