chore(deps): update tower requirement from 0.4.8 to 0.5.2

Updates the requirements on [tower](https://github.com/tower-rs/tower) to permit the latest version.
- [Release notes](https://github.com/tower-rs/tower/releases)
- [Commits](https://github.com/tower-rs/tower/compare/tower-0.4.8...tower-0.5.2)

---
updated-dependencies:
- dependency-name: tower
  dependency-version: 0.5.2
  dependency-type: direct:production
...

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

poem/Cargo.toml

@@ -115,7 +115,7 @@ async-compression = { version = "0.4.0", optional = true, features = [
     "deflate",
     "zstd",
 ] }
-tower = { version = "0.4.8", optional = true, default-features = false, features = [
+tower = { version = "0.5.2", optional = true, default-features = false, features = [
     "util",
     "buffer",
 ] }