minor refactor

Author: sebsto

Sources/AWSLambdaDeploymentDescriptor/DeploymentDefinition.swift

@@ -5,7 +5,7 @@ import Foundation
 //
 public struct DeploymentDefinition {
 
-    private var deployment : DeploymentDescriptor 
+    private let deployment : DeploymentDescriptor 
 
     public init (
         // the description of the SAM template