Bump digest/signature dependencies to new prereleases (#410)

Bumps the following:

- `digest` v0.11.0-pre.8
- `signature` v2.3.0-pre.3
- `sha1` v0.11.0-pre.3
- `sha2` v0.11.0-pre.3

Cargo.toml

@@ -19,16 +19,16 @@ num-integer = { version = "0.1.39", default-features = false }
 rand_core = { version = "0.6.4", default-features = false }
 const-oid = { version = "=0.10.0-pre.2", default-features = false }
 subtle = { version = "2.1.1", default-features = false }
-digest = { version = "=0.11.0-pre.7", default-features = false, features = ["alloc", "oid"] }
+digest = { version = "=0.11.0-pre.8", default-features = false, features = ["alloc", "oid"] }
 pkcs1 = { version = "=0.8.0-pre.0", default-features = false, features = ["alloc", "pkcs8"] }
 pkcs8 = { version = "=0.11.0-pre.0", default-features = false, features = ["alloc"] }
-signature = { version = "=2.3.0-pre.2", default-features = false , features = ["alloc", "digest", "rand_core"] }
+signature = { version = "=2.3.0-pre.3", default-features = false , features = ["alloc", "digest", "rand_core"] }
 spki = { version = "=0.8.0-pre.0", default-features = false, features = ["alloc"] }
 zeroize = { version = "1.5", features = ["alloc"] }
 
 # optional dependencies
-sha1 = { version = "=0.11.0-pre.2", optional = true, default-features = false, features = ["oid"] }
-sha2 = { version = "=0.11.0-pre.2", optional = true, default-features = false, features = ["oid"] }
+sha1 = { version = "=0.11.0-pre.3", optional = true, default-features = false, features = ["oid"] }
+sha2 = { version = "=0.11.0-pre.3", optional = true, default-features = false, features = ["oid"] }
 serde = { version = "1.0.184", optional = true, default-features = false, features = ["derive"] }
 
 [dev-dependencies]
@@ -40,9 +40,9 @@ rand_xorshift = "0.3"
 rand_chacha = "0.3"
 rand = "0.8"
 rand_core = { version = "0.6", default-features = false }
-sha1 = { version = "=0.11.0-pre.2", default-features = false, features = ["oid"] }
-sha2 = { version = "=0.11.0-pre.2", default-features = false, features = ["oid"] }
-sha3 = { version = "=0.11.0-pre.2", default-features = false, features = ["oid"] }
+sha1 = { version = "=0.11.0-pre.3", default-features = false, features = ["oid"] }
+sha2 = { version = "=0.11.0-pre.3", default-features = false, features = ["oid"] }
+sha3 = { version = "=0.11.0-pre.3", default-features = false, features = ["oid"] }
 
 [[bench]]
 name = "key"