🐛 Missing UTC indicator ('Z') in deployment timestamps

[PeRobin]

Description of the bug

The timestamps in the /designer/api/{org}/{app}/deployments endpoint in Altinn Studio are not consistently formatted in UTC. Specifically, the started and finished fields in the /deployments API response are missing the 'Z' suffix, which indicates UTC time. This can lead to incorrect local time displays, particularly during daylight saving time changes.

Expected Behavior

• All timestamps returned from the API should be in a standardized UTC format, including the 'Z' suffix (e.g., 2024-03-17T12:00:00Z), so the correct time is showed in the GUI.
• The started and finished fields in the /deployments API should follow the same UTC format as other endpoints, such as /releases.

Actual Behavior

• The /releases API correctly returns timestamps in UTC format.
• The /deployments API does not include the 'Z' suffix in the started and finished fields, causing potential time discrepancies when displayed.

📋Example:

For example, in Norway (currently in wintertime), the displayed deployment time is off by one hour.

The above version was deployed 10:46 but is displayed as 09:46.

Steps To Reproduce

1. Publish a new version of an application in Altinn Studio.
2. Retrieve deployment details via the API: GET /designer/api/{org}/{app}/deployments
3. Observe that the started and finished fields in /deployments lack the 'Z' suffix, unlike for example timestamps in /releases.

Additional Information

✅ Correct UTC format in /releases API:

❌ Incorrect timestamp format in /deployments API (started & finished missing 'Z'):

🩹 Suggested Fix
Ensure that all timestamps in the /deployments API response follow the correct UTC format (ISO 8601 with 'Z' suffix) to maintain consistency across endpoints.

📝 Environment
Platform: Altinn Studio
API Endpoint: https://altinn.studio/designer/api/{org}/{app}/deployments
Reproducibility: 100%