Update input_module_cortex_xdr.py

Description

Minor Fix in code

Motivation and Context

Issue: In order to fetch details of incidents, helper, client, incident are the params which are necessary (fetch_incident_details function); 'client' is defined in the fix.

How Has This Been Tested?

Screenshots (if appropriate)

Types of changes

• Bug fix (non-breaking change which fixes an issue)

Checklist

• [x] I have updated the documentation accordingly.
• [x] I have read the CONTRIBUTING document.
• [x] I have added tests to cover my changes if appropriate.
• [] All new and existing tests passed. (Needs to be tested)

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