fix: replace deprecated JSON encoding

[NabDevs]

Replaces deprecated GuzzleHttp\Utils::jsonEncode() calls with native json_encode(..., JSON_THROW_ON_ERROR) in the generated API clients and OpenAPI template.

Resolves INT-1795

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 68.23%. Comparing base (5e7e49e) to head (5d55871).
⚠️ Report is 1 commits behind head on v11.

Additional details and impacted files

@@            Coverage Diff            @@
##                v11     #635   +/-   ##
=========================================
  Coverage     68.23%   68.23%           
  Complexity     1363     1363           
=========================================
  Files            83       83           
  Lines          3752     3752           
=========================================
  Hits           2560     2560           
  Misses         1192     1192           

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[Copilot]

Pull request overview

This PR removes usage of the deprecated GuzzleHttp\Utils::jsonEncode() helper from generated PHP API clients by switching to native json_encode(..., JSON_THROW_ON_ERROR), and updates the OpenAPI generator template plus tests to enforce the change.

Changes:

• Replace deprecated \GuzzleHttp\Utils::jsonEncode() calls in generated API request builders with json_encode(..., JSON_THROW_ON_ERROR).
• Add test coverage to ensure generated clients no longer reference the deprecated helper and that invalid JSON payloads now throw JsonException.
• Introduce/override the OpenAPI Generator api.mustache template to generate the new encoding behavior and document JsonException.

Reviewed changes

Copilot reviewed 2 out of 10 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
test/Client/GeneratedJsonEncodingTest.php	Adds a safety test to ensure generated API classes don’t contain deprecated Utils::jsonEncode calls.
test/Client/Generated/CoreApi/ShipmentApiPostShipmentsTest.php	Adds a regression test asserting JsonException on invalid JSON payload encoding.
src/Client/Generated/OrderApi/Api/DefaultApi.php	Replaces deprecated JSON encoding helper with native json_encode(..., JSON_THROW_ON_ERROR) and documents JsonException.
src/Client/Generated/IamApi/Api/DefaultApi.php	Updates JSON encoding of form params to native json_encode(..., JSON_THROW_ON_ERROR) and documents JsonException.
src/Client/Generated/CoreApiPrivate/Api/ShippingRuleApi.php	Updates JSON encoding of form params/body to native json_encode(..., JSON_THROW_ON_ERROR) and documents JsonException.
src/Client/Generated/CoreApi/Api/WebhookApi.php	Updates JSON encoding of form params/body to native json_encode(..., JSON_THROW_ON_ERROR) and documents JsonException.
src/Client/Generated/CoreApi/Api/ShipmentApi.php	Updates JSON encoding of form params/body to native json_encode(..., JSON_THROW_ON_ERROR) and documents JsonException.
src/Client/Generated/CoreApi/Api/NotificationApi.php	Updates JSON encoding of form params/body to native json_encode(..., JSON_THROW_ON_ERROR) and documents JsonException.
src/Client/Generated/CoreApi/Api/DefaultApi.php	Updates JSON encoding of form params to native json_encode(..., JSON_THROW_ON_ERROR) and documents JsonException.
openapi/templates/api.mustache	Overrides generator template to emit native JSON encoding with JSON_THROW_ON_ERROR and add JsonException to docs.

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