feat(valkey): add Valkey module (#947)

I’d like to add Valkey, the open-source fork of Redis, as a dedicated
Testcontainers module.

- Docker container: valkey/valkey:latest
- Valkey website: https://valkey.io/
- Documentation: https://valkey.io/docs/

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Signed-off-by: Daria Korenieva <daric2612@gmail.com>
Co-authored-by: Roy Moore <roy@moore.co.il>