fix: AB test variant fields nullability (#720)

Author: VladislavFitz

Sources/AlgoliaSearchClient/Models/Analytics/ABTest/Response/ABTestResponse+Variant.swift

@@ -10,18 +10,18 @@ import Foundation
 extension ABTestResponse {
 
   public struct Variant: Codable {
+    
+    public let indexName: IndexName
+
+    public let trafficPercentage: Int
 
     /// Distinct click count for the variant.
-    public let clickCount: Int
+    public let clickCount: Int?
 
     /// Distinct conversion count for the variant.
-    public let conversionCount: Int
-
-    public let description: String
+    public let conversionCount: Int?
 
-    public let indexName: IndexName
-
-    public let trafficPercentage: Int
+    public let description: String?
 
     /// Conversion rate for the variant.
     public let conversionRate: Double?

Sources/AlgoliaSearchClient/Models/Analytics/ABTest/Response/ABTestResponse.swift

@@ -17,7 +17,7 @@ public struct ABTestResponse {
   public let clickSignificance: Double?
 
   /// ABTest significance based on conversion data.
-  /// Should be > 0.95 to be considered significant (no matter which variant is winning
+  /// Should be > 0.95 to be considered significant (no matter which variant is winning)
   public let conversionSignificance: Double?
 
   /// Time at which the ABTest  has been created.