Add optional org_id field to AppleIdentityToken (#94)

Sources/JWTKit/Vendor/AppleIdentityToken.swift

@@ -11,6 +11,7 @@ public struct AppleIdentityToken: JWTPayload {
         case emailVerified = "email_verified"
         case isPrivateEmail = "is_private_email"
         case nonceSupported = "nonce_supported"
+        case orgId = "org_id"
     }
 
     /// The issuer-registered claim key, which has the value https://appleid.apple.com.
@@ -40,6 +41,9 @@ public struct AppleIdentityToken: JWTPayload {
     /// The user's email address.
     public let email: String?
 
+    /// Managed Apple ID organization (see https://developer.apple.com/documentation/rosterapi/integrating_with_roster_api_and_sign_in_with_apple)
+    public let orgId: String?
+
     /// A Boolean value that indicates whether the service has verified the email. The value of this claim is always true because the servers only return verified email addresses.
     public let emailVerified: BoolClaim?