Hitless upgrade support implementation for synchronous Redis client.

[petyaslavova]

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Description of change

Hitless upgrade support implementation for synchronous Redis client.

[Copilot]

Pull Request Overview

This PR adds hitless upgrade support for the synchronous Redis client by implementing maintenance event handling and extending the connection and parser layers to react to MOVING, MIGRATING, and MIGRATED push messages.

• Introduce a new MaintenanceEventsConfig, connection and pool handlers to manage maintenance event lifecycles.
• Update the Connection, ConnectionPool, and Redis client to wire up maintenance event handlers when RESP3 is used.
• Add extensive unit and integration tests covering event parsing, pool behavior, and client operations during node maintenance.

Reviewed Changes

Copilot reviewed 11 out of 11 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
tests/test_maintenance_events_handling.py	New integration tests for MOVING/MIGRATING/MIGRATED event handling
tests/test_maintenance_events.py	Unit tests for MaintenanceEvent* classes and pool/connection handlers
tests/test_connection_pool.py	Add should_reconnect stub for pool tests
redis/retry.py	Log a warning on each retry attempt
redis/maintenance_events.py	Core implementation of maintenance event parsing and pool handler
redis/connection.py	Extend AbstractConnection to support maintenance events
redis/client.py	Wire maintenance event config into Redis client
redis/_parsers/resp3.py	Hook maintenance push handlers into RESP3 parser
redis/_parsers/hiredis.py	Hook maintenance push handlers into Hiredis parser
redis/_parsers/base.py	Define maintenance message types and dispatch to handlers
redis/asyncio/connection.py	Add maintenance lock scope to asyncio pool

Comments suppressed due to low confidence (1)

redis/_parsers/resp3.py:209

• Using a hardcoded id for all MOVING notifications can cause event collisions and prevent correct deduplication; consider parsing a unique ID from the server message or incrementing per‐event.

        # bulk response