feat: add redis-caching

[alonexy]

feat: Add Redis caching layer for policies
This commit introduces a Redis caching layer to the DBAL adapter to improve performance and reduce database load.

Features:

Policies loaded via loadPolicy and loadFilteredPolicy are now cached in Redis.
Configurable Redis connection parameters (host, port, password, database, TTL, prefix).
Automatic cache invalidation for the main policy cache (all_policies) when policies are modified.
A preheatCache() method to proactively load all policies into Redis.
The adapter remains fully functional if Redis is not configured.
Includes:

Updates to Adapter.php to integrate caching logic.
Addition of predis/predis as a dependency.
Unit tests for the caching functionality in AdapterWithRedisTest.php.
Documentation in README.md for the new feature.
Known limitations:

Cache invalidation for loadFilteredPolicy currently only clears the global all_policies key, not specific filtered policy keys, to avoid using KEYS in production with Predis.

[leeqvip]

@alonexy Please fix test error