fix: register EmbeddedObjectConverter in ContentstackClient constructor

[OMpawar-21]

Summary

• Register EmbeddedObjectConverter in ContentstackClient constructor so .includeEmbeddedItems().Fetch<T>() deserializes _embedded_items without crashing when the model implements IEntryEmbedable
• Bump contentstack.utils dependency to 1.4.0 which ships the concrete EmbeddedObject class and EmbeddedObjectConverter
• Version bump to 2.28.0

Problem

Customers calling .includeEmbeddedItems().Fetch<T>() on a model implementing IEntryEmbedable received a JsonSerializationException at runtime whenever the Delivery API returned _embedded_items in the response:

Could not create an instance of type Contentstack.Utils.Interfaces.IEmbeddedObject.
Type is an interface or abstract class and cannot be instantiated.
Path 'entry._embedded_items.rte_json[0]._content_type_uid'

IEntryEmbedable.embeddedItems is typed as Dictionary<string, List<IEmbeddedObject>>. With no JsonConverter registered, Newtonsoft.Json tried to new() the interface directly and threw.

Changes

ContentstackClient.cs

One line added in the constructor after the existing CSJsonConverterAttribute loop:

// Handles deserialization of embedded entries and assets in _embedded_items responses.
SerializerSettings.Converters.Add(new EmbeddedObjectConverter());

[github-actions]

🔒 Security Scan Results

ℹ️ Note: Only vulnerabilities with available fixes (upgrades or patches) are counted toward thresholds.

Check Type	Count (with fixes)	Without fixes	Threshold	Result
🔴 Critical Severity	0	0	10	✅ Passed
🟠 High Severity	0	0	25	✅ Passed
🟡 Medium Severity	0	0	500	✅ Passed
🔵 Low Severity	0	0	1000	✅ Passed

⏱️ SLA Breach Summary

✅ No SLA breaches detected. All vulnerabilities are within acceptable time thresholds.

Severity	Breaches (with fixes)	Breaches (no fixes)	SLA Threshold (with/no fixes)	Status
🔴 Critical	0	0	15 / 30 days	✅ Passed
🟠 High	0	0	30 / 120 days	✅ Passed
🟡 Medium	0	0	90 / 365 days	✅ Passed
🔵 Low	0	0	180 / 365 days	✅ Passed

✅ BUILD PASSED - All security checks passed