Enable std feature for rand_core

With the std feature enabled, rand_core::Error implements
std::error::Error, which we require for the error types wrapped in the
Error enum.

1 files changed, 1 insertions, 1 deletions

diff --git a/Cargo.toml b/Cargo.toml
index cfe1579..ceaa57d 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -15,7 +15,7 @@ license = "MIT"
 [dependencies]
 libc = "0.2"
 nitrokey-sys = "3.4"
-rand_core = {version = "0.3", default-features = false}
+rand_core = {version = "0.3", default-features = false, features = ["std"] }
 rand_os = {version = "0.1"}
 
 [dev-dependencies]