ssh-key: update prerelease dependency requirements (#520)

Author: tarcieri

ssh-key/Cargo.toml

@@ -38,15 +38,15 @@ zeroize = { version = "1", default-features = false }
 # optional dependencies
 argon2 = { version = "0.6.0-rc.8", optional = true, default-features = false, features = ["alloc"] }
 bcrypt-pbkdf = { version = "0.11", optional = true, default-features = false, features = ["alloc"] }
-dsa = { version = "0.7.0-rc.14", optional = true, default-features = false, features = ["hazmat"] }
+dsa = { version = "0.7.0-rc.15", optional = true, default-features = false, features = ["hazmat"] }
 ed25519-dalek = { version = "3.0.0-pre.7", optional = true, default-features = false }
 hex = { version = "0.4", optional = true, default-features = false, features = ["alloc"] }
 hmac = { version = "0.13", optional = true }
 p256 = { version = "0.14.0-rc.9", optional = true, default-features = false, features = ["ecdsa"] }
 p384 = { version = "0.14.0-rc.9", optional = true, default-features = false, features = ["ecdsa"] }
 p521 = { version = "0.14.0-rc.9", optional = true, default-features = false, features = ["ecdsa"] }
 rand_core = { version = "0.10", optional = true, default-features = false }
-rsa = { version = "0.10.0-rc.17", optional = true, default-features = false, features = ["sha2"] }
+rsa = { version = "0.10.0-rc.18", optional = true, default-features = false, features = ["sha2"] }
 sec1 = { version = "0.8", optional = true, default-features = false, features = ["point"] }
 serde = { version = "1.0.16", optional = true }
 sha1 = { version = "0.11", optional = true, default-features = false, features = ["oid"] }