fixing mypy issues

[v-dharmarajv]

Description

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Testing Guidelines

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[github-actions]

API Change Check

APIView identified API level changes in this PR and created the following API reviews

azure-communication-callautomation

[Copilot]

Pull Request Overview

This pull request addresses MyPy type checking issues in the Azure Communication Call Automation SDK. The changes focus on resolving type annotation errors by adding explicit type ignores, improving null safety, and adding proper type casting.

Key Changes

• Added type ignore comments for credential and argument type mismatches
• Improved null safety with fallback values for optional parameters
• Added explicit type casting to resolve type checker warnings

Reviewed Changes

Copilot reviewed 13 out of 13 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
samples/create_call_sample.py	Added fallback value for connection string environment variable
mypy.ini	Added MyPy configuration file with relaxed settings
aio/_content_downloader_async.py	Fixed hostname null safety and client attribute access
aio/_call_connection_client_async.py	Added type ignores and improved parameter handling
aio/_call_automation_client_async.py	Fixed type casting and async iterator implementation
_utils.py	Added explicit type casting for identifier serialization
_shared/models.py	Added type ignores for identifier return types
_models.py	Improved null safety in model generation methods
_generated/models/_models.py	Added datetime import
_content_downloader.py	Fixed hostname null safety
_call_connection_client.py	Added type ignores and improved casting
_call_automation_client.py	Fixed type casting and parameter handling
apiview-properties.json	Added new API view configuration file