Update rcgen requirement from 0.10.0 to 0.11.1 (#597)

Updates the requirements on [rcgen](https://github.com/est31/rcgen) to permit the latest version.
- [Changelog](https://github.com/est31/rcgen/blob/master/CHANGELOG.md)
- [Commits](rustls/rcgen@v0.10.0...v0.11.1)

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

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

poem/Cargo.toml

@@ -153,7 +153,7 @@ hyper-rustls = { workspace = true, optional = true, features = [
     "tls12",
     "logging",
 ] }
-rcgen = { version = "0.10.0", optional = true }
+rcgen = { version = "0.11.1", optional = true }
 x509-parser = { version = "0.15.0", optional = true }
 tokio-metrics = { version = "0.2.0", optional = true }
 rust-embed = { version = "6.3", optional = true }