.Net: Handlebars prompt template doesn't deserialize JSON response when Content-Type includes charset

[vsomayaji]

Describe the bug
If the Content-Type header of a REST API JSON response includes a charset (e.g. Content-Type: application/json; charset=utf-8), the Handlebars prompt template handles the response as a string instead of as deserialized JSON.

To Reproduce
The issue appears to be due to how the Content-Type is matched here:

semantic-kernel/dotnet/src/Extensions/PromptTemplates.Handlebars/Helpers/KernelHelpers/KernelFunctionHelpers.cs

Lines 211 to 221 in fe29d1a

	if (resultAsObject is RestApiOperationResponse restApiOperationResponse)
	{
	// Deserialize any JSON content or return the content as a string
	if (string.Equals(restApiOperationResponse.ContentType, "application/json", StringComparison.OrdinalIgnoreCase))
	{
	var parsedJson = JsonValue.Parse(restApiOperationResponse.Content.ToString());
	return KernelHelpersUtils.DeserializeJsonNode(parsedJson);
	}
	return restApiOperationResponse.Content;
	}

Expected behavior
The JSON response should be deserialized.

Platform

• Language: C#
• Source: Microsoft.SemanticKernel.PromptTemplates.Handlebars version 1.4.0