chore(deps): Update ecdsa requirement from 0.15 to 0.16

Updates the requirements on [ecdsa](https://github.com/RustCrypto/signatures) to permit the latest version.
- [Release notes](https://github.com/RustCrypto/signatures/releases)
- [Commits](RustCrypto/signatures@ecdsa/v0.15.0...ecdsa/v0.16.0)

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

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

Cargo.toml

@@ -57,7 +57,7 @@ chrono = { version = "0.4.23", feature = "clock" }
 const-oid = "0.9.1"
 der = "0.6.1"
 digest = { version = "0.10.3", default-features = false }
-ecdsa = { version = "0.15", features = [ "pkcs8", "digest", "der" ] }
+ecdsa = { version = "0.16", features = [ "pkcs8", "digest", "der" ] }
 ed25519 = { version = "=2.1", features = [ "alloc" ] }
 ed25519-dalek = { version = "2.0.0-pre.0", features = [ "pkcs8", "rand_core" ] }
 elliptic-curve = { version = "0.12.2", features = [ "arithmetic", "pem" ] }