updated TaskSatus enum

[andrewelamb]

Problem:

• The TaskState enum in synapseclient/models/curation.py was out of sync with the Synapse REST API.
• The API documents six task states, but the client only defined four (NOT_STARTED, IN_PROGRESS, COMPLETED, CANCELED).
• The two missing states — EXECUTING and IN_REVIEW — are returned by the API when a task has an automated async job running or awaiting review. Deserializing a CurationTask in one of these states would fail to coerce into a valid TaskState.
• Reference: TaskState

Solution:

• Added the two missing enum members to TaskState, matching the names, values, and ordering in the REST docs:
  • EXECUTING — "An automated execution (async job) is currently running for this task."
  • IN_REVIEW — "The automated execution completed successfully and the results are pending human review."
• Each member carries the documented description as its docstring, consistent with the existing states.