[URGENT] Set JsonStringConverter to JSON deserializer option in WattTimeClient

[YaSuenag]

Pull Request

@vaughanknight @danuw Please review this PR. I think it is urgent bug.

Summary

co2_moer and co2_aoer have been supported since #611 , however WattTime client is possibility not to work after this change.

#611 introduces these values as enum, not `stiring. It might cause deserialization error.

fail: CarbonAware.WebApi.Filters.HttpResponseExceptionFilter[0]
      Exception: The JSON value could not be converted to CarbonAware.DataSources.WattTime.Constants.SignalTypes. Path: $.signal_type | LineNumber: 0 | BytePositionInLine: 102.
      System.Text.Json.JsonException: The JSON value could not be converted to CarbonAware.DataSources.WattTime.Constants.SignalTypes. Path: $.signal_type | LineNumber: 0 | BytePositionInLine: 102.
         at System.Text.Json.ThrowHelper.ThrowJsonException(String message)
         at System.Text.Json.Serialization.Converters.EnumConverter`1.Read(Utf8JsonReader& reader, Type typeToConvert, JsonSerializerOptions options)
         at System.Text.Json.Serialization.Metadata.JsonPropertyInfo`1.ReadJsonAndSetMember(Object obj, ReadStack& state, Utf8JsonReader& reader)
         at System.Text.Json.Serialization.Converters.ObjectDefaultConverter`1.OnTryRead(Utf8JsonReader& reader, Type typeToConvert, JsonSerializerOptions options, ReadStack& state, T& value)
         at System.Text.Json.Serialization.JsonConverter`1.TryRead(Utf8JsonReader& reader, Type typeToConvert, JsonSerializerOptions options, ReadStack& state, T& value, Boolean& isPopulatedValue)
         at System.Text.Json.Serialization.JsonConverter`1.ReadCore(Utf8JsonReader& reader, JsonSerializerOptions options, ReadStack& state)
         at System.Text.Json.Serialization.Metadata.JsonTypeInfo`1.ContinueDeserialize(ReadBufferState& bufferState, JsonReaderState& jsonReaderState, ReadStack& readStack)
         at System.Text.Json.Serialization.Metadata.JsonTypeInfo`1.DeserializeAsync(Stream utf8Json, CancellationToken cancellationToken)
         at CarbonAware.DataSources.WattTime.Client.WattTimeClient.<>c__DisplayClass34_0.<<GetRegionFromCacheAsync>b__0>d.MoveNext() in /app/CarbonAware.DataSources/CarbonAware.DataSources.WattTime/src/Client/WattTimeClient.cs:line 315 

WattTime respond as following in this case. It was expected.

{
  "region": "CAISO",
  "region_full_name": "California Independent System Operator",
  "signal_type": "co2_aoer"
}

Changes

• Set JsonStringEnumConverter to JSON deserializer option.

Checklist

• Local Tests Passing?
• CICD and Pipeline Tests Passing?
• Added any new Tests?
• Documentation Updates Made?
• Are there any API Changes? If yes, please describe below.
• This is not a breaking change. If it is, please describe it below.

Are there API Changes?

No

Is this a breaking change?

No

[danuw]

thank you

[danuw]

Can we get at least one unit test that helps us spot if a change is likely to introduce this back please?

[Copilot]

Copilot reviewed 1 out of 1 changed files in this pull request and generated no comments.