Add rand crate as a dev-dependency

Will be required for testing the Unix peer credentials authenticator.

Signed-off-by: Joe Ellis <joe.ellis@arm.com>

Author: Joe Ellis

Cargo.toml

@@ -44,6 +44,9 @@ picky-asn1-x509 = { version = "0.3.2", optional = true }
 users = "0.10.0"
 libc = "0.2.77"
 
+[dev-dependencies]
+rand = { version = "0.7.3", features = ["small_rng"] }
+
 [package.metadata.docs.rs]
 features = ["pkcs11-provider", "tpm-provider", "tss-esapi/docs", "mbed-crypto-provider"]