Dependency maintenance: refresh to Serializable 0.10.2 cascade

[LK-Simon]

Summary

Refresh ESPressio Event after the Serializable 0.10.2 downstream cascade.

Scope

• Prepare ESPressio Event 5.8.2.
• Consume Serializable 0.10.2 directly for Event Transport.
• Consume the released Units 0.2.3, Timing 2.2.4, Threads 3.1.4 and ESP-Now 0.5.2 generation as appropriate.
• Refresh README, changelog, dependency chart, package metadata and CI validation.
• Do not strengthen the Event↔ESP-Now or Event↔Sockets reciprocal optional dependencies.

Release

Target patch release: 5.8.2.