fix: Re-add futures dependency to resolve CI/CD build failure

- Add futures = "0.3" dependency back to Cargo.toml
- Required for async operations in cache.rs tests
- Resolves error: use of unresolved module or unlinked crate 'futures'
- CI/CD pipeline should now pass successfully

This dependency is actually needed for the async cache manager operations.

Cargo.toml

@@ -38,6 +38,7 @@ tracing-appender = "0.2"
 
 # Async runtime (used for concurrent operations)
 tokio = { version = "1.0", features = ["full"] }
+futures = "0.3"
 
 # D-Bus integration (used for daemon communication)
 zbus = "4.0"