task_agent_client get_environment_deployment_execution_records does not return a continuation token

[leyshon]

The get_environment_deployment_execution_records method in the task_agent_client will accept a continuation token as a parameter but does not return one when called. This means it is not possible to correctly page through the results.

I note that a similar issue for the get_builds method in the build_client was fixed here #152. Hopefully it's a case of adding something similar this https://github.com/microsoft/azure-devops-python-api/blob/dev/azure-devops/azure/devops/v5_1/build/build_client.py#L450