Check Redis server before hash field TTL

[sakshichitnis27]

Fixes #829

Summary

Check the connected Redis server version before using hash field expiration commands. This prevents HashModel.save() from calling HTTL on Redis versions older than 7.4.

Added regression tests for supported and unsupported server versions.

Testing

• Verified the fix against Redis 7.2.14
• pytest -q -n auto ./tests/ ./tests_sync/

Fixes #829

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Note

Medium Risk
Changes persistence paths for HashModel saves and field TTL APIs; behavior shifts on Redis < 7.4 (skips HTTL/HEXPIRE) but avoids runtime errors—worth verifying against production Redis versions.

Overview
Hash field expiration (HTTL / HEXPIRE on HashModel.save() and related APIs) is now gated on the connected Redis server version, not only redis-py ≥ 5.1.0. supports_hash_field_expiration(conn) is async, takes a connection, and returns false unless INFO server reports Redis 7.4+; failures from Redis or parsing are swallowed and treated as unsupported.

HashModel.save() and expire_field / field_ttl / persist_field await that check with self.db() so older servers (e.g. 7.2) no longer hit unsupported commands during ordinary saves. Tests add parametrized server-version coverage and update the existing support probe to pass the fixture client.

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[sakshichitnis27]

Hi maintainers,
I’ve opened PR #841 to address this issue. Please let me know if any changes or additional tests are needed. I’d be happy to update it. Thanks!