parse .p8 file content from env values

Author: andygruening

Assets/SequenceSDK/Editor/TestflightUploadPostBuildScript.cs

@@ -26,6 +26,7 @@ public void OnPostprocessBuild(BuildReport report)
             var keyId = Environment.GetEnvironmentVariable("APPSTORE_CONNECT_KEY_ID");
             var issuerId = Environment.GetEnvironmentVariable("APPSTORE_CONNECT_ISSUER_ID");
             var privateKey = Environment.GetEnvironmentVariable("APPSTORE_CONNECT_P8");
+            privateKey = privateKey?.Replace("\\n", "\n");
 
             var keyDir = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.UserProfile), ".appstoreconnect/private_keys");