digest: bump sha2 dev-dependency to v0.11 (#2345)

Author: tarcieri

Cargo.lock

@@ -23,7 +23,7 @@ ctutils = { version = "0.4", optional = true }
 zeroize = { version = "1.7", optional = true, default-features = false }
 
 [dev-dependencies]
-sha2 = "0.11.0-rc.5"
+sha2 = "0.11"
 
 [features]
 default = ["block-api"]