Update jsonwebtoken requirement from 8.0 to 9.1

Updates the requirements on [jsonwebtoken](https://github.com/Keats/jsonwebtoken) to permit the latest version.
- [Changelog](https://github.com/Keats/jsonwebtoken/blob/master/CHANGELOG.md)
- [Commits](Keats/jsonwebtoken@v8.0.0...v9.1.0)

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

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

middleware/jwt/Cargo.toml

@@ -17,6 +17,6 @@ edition = "2018"
 [dependencies]
 futures-util = "0.3.14"
 gotham = { path = "../../gotham", version = "0.7.2", default-features = false, features = ["derive"] }
-jsonwebtoken = { version = "8.0", default-features = false }
+jsonwebtoken = { version = "9.1", default-features = false }
 log = "0.4"
 serde = { version = "1.0", features = ["derive"] }