Update rasn requirement from 0.18.0 to 0.20.1 in /sdk

Updates the requirements on [rasn](https://github.com/librasn/rasn) to permit the latest version.
- [Release notes](https://github.com/librasn/rasn/releases)
- [Changelog](https://github.com/librasn/rasn/blob/main/CHANGELOG.md)
- [Commits](librasn/rasn@rasn-v0.18.0...rasn-v0.20.1)

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

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

sdk/Cargo.toml

@@ -109,7 +109,7 @@ rand_chacha = "0.3.1"
 range-set = "0.0.11"
 rasn-ocsp = "0.18.0"
 rasn-pkix = "0.18.0"
-rasn = "0.18.0"
+rasn = "0.20.1"
 riff = "2.0.0"
 schemars = { version = "0.8.21", optional = true }
 serde = { version = "1.0.197", features = ["derive"] }