magda-dap-connector generates date string that doesn't match JSON schema

[t83714]

Describe the bug

magda-dap-connector generates date string that doesn't match JSON schema for dcat-dataset-strings aspect

Failed to PUT data registry record with ID "dist-dap-9908911". 4 retries left. Status code: 400, body:
{
  "message": "#/issued: [] is not a valid date-time. Expected [yyyy-MM-dd'T'HH:mm:ssZ, yyyy-MM-dd'T'HH:mm:ss.[0-9]{1,9}Z, yyyy-MM-dd'T'HH:mm:ss[+-]HH:mm, yyyy-MM-dd'T'HH:mm:ss.[0-9]{1,9}[+-]HH:mm]"
}
Failed to PUT data registry record with ID "dist-dap-9908911". 3 retries left. Status code: 400, body:
{
  "message": "#/issued: [] is not a valid date-time. Expected [yyyy-MM-dd'T'HH:mm:ssZ, yyyy-MM-dd'T'HH:mm:ss.[0-9]{1,9}Z, yyyy-MM-dd'T'HH:mm:ss[+-]HH:mm, yyyy-MM-dd'T'HH:mm:ss.[0-9]{1,9}[+-]HH:mm]"
}

To Reproduce

Deploy magda-dap-connector with config:

    id: dap
    name: CSIRO
    sourceUrl: https://data.csiro.au/dap/ws/v2/
    pageSize: 100

Make sure validateJsonSchema option is true to turn json validation on