chore(deps): Update aws-sigv4 requirement from 0.14 to 0.15 (#93)

Updates the requirements on [aws-sigv4](/~https://github.com/awslabs/smithy-rs) to permit the latest version.
- [Release notes](/~https://github.com/awslabs/smithy-rs/releases)
- [Changelog](/~https://github.com/awslabs/smithy-rs/blob/main/CHANGELOG.md)
- [Commits](smithy-lang/smithy-rs@v0.14...v0.15)

---
updated-dependencies:
- dependency-name: aws-sigv4
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

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

Cargo.toml

@@ -45,7 +45,7 @@ sha2 = "0.10"
 time = { version = "0.3.9", features = ["macros", "formatting", "parsing"] }
 
 [dev-dependencies]
-aws-sigv4 = "0.14"
+aws-sigv4 = "0.15"
 criterion = { version = "0.3", features = ["async_tokio", "html_reports"] }
 dotenv = "0.15"
 env_logger = "0.9"