Upgrade serde_yaml

[CeerDecy]

What this PR does / why we need it:

the package yaml-rust seems unmaintained, and the serde_yaml v0.8.26 depends on it, so upgrade the serde_yaml version to 0.9.
The new version of serde_yaml no longer supports the syntax standard: {} to automatically inject default values for enum types, need to add singleton_map annotations in discovery-handlers/opcua/src/discovery_handler.rs Line 55. references serde_yaml issue

closes #693

Special notes for your reviewer:

If applicable:

• this PR has an associated PR with documentation in akri-docs
• this PR contains unit tests
• added code adheres to standard Rust formatting (cargo fmt)
• code builds properly (cargo build)
• code is free of common mistakes (cargo clippy)
• all Akri tests succeed (cargo test)
• inline documentation builds (cargo doc)
• all commits pass the DCO bot check by being signed off -- see the failing DCO check for instructions on how to retroactively sign commits