zvariant-2.9.0

• Add as_ref to borrow string wrappers.
• Advance signature parser by correct number for byte arrays.
• Implement TryFrom<Value<'a>> for HashMap.
• Broaden Error restriction on TryFrom bounds.
• Add OwnedFd.
• Some formatting improvements.
• Add non-owning helpers to StructureBuilder.
• Add DynamicType + DynamicDeserialize for Array.
• Add DynamicType + DynamicDeserialize for Structure.
• Add deserialization functions using DynamicDeserialize.
• Add From impl for &Signature.
• Support structures with runtime-defined signatures.
• Introduce DynamicType and DynamicDeserialize.
• Introduce new signature mismatch error.
• Dependency changes:
  • Add libc dependency.