Add ssl_password support to async Redis client

[majiayu000]

Summary

Fixes #3347

Add ssl_password parameter to the async Redis client and SSLConnection to enable using encrypted private keys, matching the sync client's functionality.

Changes

• Add ssl_password parameter to Redis.__init__
• Add ssl_password parameter to SSLConnection.__init__
• Add password parameter to RedisSSLContext
• Pass password to ssl.SSLContext.load_cert_chain()

Usage

from redis.asyncio import Redis

client = Redis(
    host="localhost",
    ssl=True,
    ssl_keyfile="/path/to/encrypted.key",
    ssl_certfile="/path/to/cert.pem",
    ssl_password="your-key-password",
)

🤖 Generated with Claude Code

[petyaslavova]

Hi @majiayu000, thank you for your contribution! Would you please add some unit tests that cover the change?

[majiayu000]

Thanks for the review! I've added a unit test (test_ssl_password_parameter) in tests/test_asyncio/test_ssl.py to verify that ssl_password is properly passed through to SSLConnection.

Please let me know if you'd like any additional test coverage.

[petyaslavova]

Hi @majiayu000, the change over all looks good. Can you please just fix the conflicts and we can merge this PR...