Update base64 dependency for nostd support

Author: roblabla

Cargo.toml

@@ -34,7 +34,7 @@ default-features = false
 features = ["derive"]
 
 [dev-dependencies]
-#base64 = "0.10.1"
+base64 = { version = "0.11.0", default-features = false }
 sha-1 = "0.8.1"
 sha2 = "0.8.0"
 hex = "0.4.0"
@@ -52,7 +52,7 @@ name = "key"
 
 [features]
 default = ["std"]
-std = ["num-bigint/std", "num-traits/std", "num-integer/std", "num-iter/std", "rand/std", "byteorder/std", "failure/std", "subtle/std"]
+std = ["num-bigint/std", "num-traits/std", "num-integer/std", "num-iter/std", "rand/std", "byteorder/std", "failure/std", "subtle/std", "base64/std"]
 nightly = ["subtle/nightly", "num-bigint/nightly"]
 serde1 = ["num-bigint/serde", "serde"]
 expose-internals = []