Update rcgen requirement from 0.11.0 to 0.12.1

Updates the requirements on [rcgen](https://github.com/rustls/rcgen) to permit the latest version.
- [Commits](rustls/rcgen@v0.11.0...v0.12.1)

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

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

Cargo.toml

@@ -27,7 +27,7 @@ futures-util = "0.3"
 parking_lot = { version = "0.12", features = ["send_guard"] }
 pin-project = "1"
 quinn = "0.10.1"
-rcgen = { version = "0.11.0", default-features = false, optional = true }
+rcgen = { version = "0.12.1", default-features = false, optional = true }
 rustls = { version = "0.21.1", default-features = false, features = [
 	"dangerous_configuration",
 ] }