make generateChallengeString public (temporary)

Author: marius-se

Sources/WebAuthn/WebAuthnManager.swift

@@ -241,7 +241,7 @@ extension WebAuthnManager {
     /// Generate a suitably random value to be used as an attestation or assertion challenge
     /// - Throws: An error if something went wrong while generating random byte
     /// - Returns: 32 bytes
-    func generateChallengeString() throws -> [UInt8] {
+    public func generateChallengeString() throws -> [UInt8] {
         var bytes = [UInt8](repeating: 0, count: 32)
         let status = SecRandomCopyBytes(kSecRandomDefault, bytes.count, &bytes)
         guard status == errSecSuccess else { throw WebAuthnManagerError.challengeGenerationFailed }