fix unicode parse error

Author: thomas-k-cameron

aws/rust-runtime/aws-credential-types/Cargo.toml

@@ -14,6 +14,7 @@ test-util = []
 [dependencies]
 aws-smithy-async = { path = "../../../rust-runtime/aws-smithy-async" }
 aws-smithy-types = { path = "../../../rust-runtime/aws-smithy-types" }
+regex = { version = "1", features = ["unicode-case"] }
 fastrand = "1.4.0"
 tokio = { version = "1.23.1", features = ["sync"] }
 tracing = "0.1"