Update virtue requirement from 0.0.14 to 0.0.15 (#673)

Updates the requirements on [virtue](https://github.com/bincode-org/virtue) to permit the latest version.
- [Release notes](https://github.com/bincode-org/virtue/releases)
- [Commits](bincode-org/virtue@v0.0.14...v0.0.15)

---
updated-dependencies:
- dependency-name: virtue
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

derive/Cargo.toml

@@ -19,4 +19,4 @@ description = "Implementation of #[derive(Encode, Decode)] for bincode"
 proc-macro = true
 
 [dependencies]
-virtue = "0.0.14"
+virtue = "0.0.15"