fix(bug): workflow client missing close function to pass to durable task

[CasperGN]

Description

The workflow client did not expose close() function (as can be seen in the go-sdk. We observed in dapr/dapr-agents that we were unable to pass our closing statement down to the durable task which meant lingering threads.

Issue reference

We strive to have all PR being opened based on an issue, where the problem or feature have been discussed prior to implementation.

Please reference the issue this PR will close: N/A

Checklist

Please make sure you've completed the relevant tasks for this PR, out of the following list:

• Code compiles correctly
• Created/updated tests
• Extended the documentation

[CasperGN]

@acroca as we discussed this depends on dapr/durabletask-python#39 + new version of Durabletask-Python. Once that has been merged I'll add a version bump to this PR and create another equivalent PR targeting release-1.17 branch

[codecov]

Codecov Report

❌ Patch coverage is 50.00000% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 86.95%. Comparing base (bffb749) to head (b9da3ad).
⚠️ Report is 63 commits behind head on main.

Files with missing lines	Patch %	Lines
...workflow/dapr/ext/workflow/dapr_workflow_client.py	50.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #889      +/-   ##
==========================================
+ Coverage   86.63%   86.95%   +0.32%     
==========================================
  Files          84      103      +19     
  Lines        4473     6900    +2427     
==========================================
+ Hits         3875     6000    +2125     
- Misses        598      900     +302     

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