Replace deprecated pyserial-asyncio with pyserial-asyncio-fast and update manifest version

[markoberholzer-es]

Summary

This PR addresses the deprecation of pyserial-asyncio which will be blocked in Home Assistant (#2).
The changes include:

• Replacing pyserial-asyncio with pyserial-asyncio-fast for serial communication.
• Updating manifest.json to reflect the new dependency and version requirements.

Motivation

pyserial-asyncio is deprecated and scheduled to be blocked in future Home Assistant releases.
Switching to pyserial-asyncio-fast ensures compatibility and continued functionality.

Changes

• Updated requirements.txt / manifest.json to use pyserial-asyncio-fast.
• Verified compatibility with existing code.
• Bumped manifest version to align with dependency update.

Testing

• Installed new dependency locally and confirmed successful import.
• Verified that serial communication works as expected.

Related Issue

Fixes #2