Update serde-xml-rs requirement from 0.6 to 0.8

Updates the requirements on [serde-xml-rs](https://github.com/RReverser/serde-xml-rs) to permit the latest version.
- [Release notes](https://github.com/RReverser/serde-xml-rs/releases)
- [Commits](RReverser/serde-xml-rs@0.6.0...0.8.0)

---
updated-dependencies:
- dependency-name: serde-xml-rs
  dependency-version: 0.8.0
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

Cargo.toml

@@ -68,7 +68,7 @@ futures = "0.3"
 io-extras = "0.18.0"
 
 # For DDS Security:
-serde-xml-rs = { version = "0.6" , optional = true } # for reading spec-mandated XML config files
+serde-xml-rs = { version = "0.8" , optional = true } # for reading spec-mandated XML config files
 glob = { version = "0.3" , optional = true } # for reading spec-mandated XML config files
 mailparse = { version = "0.15" , optional = true } # for reading S/MIME-encoded (XML) config files
 x509-certificate = { version = "0.24" , optional = true } # for configuration certificates