fix: Fixing a crash when attempting to call finishWriting

[ruisebas]

Issue #, if available:

• https://github.com/aws-amplify/amplify-ui-swift-liveness/issues/148

Description of changes:

This PR attempts to fix an NSInternalInconsistencyException crash that might be happening when calling AVAssetWriter.finishWriting on an instance that is already completed.

There was a previous validation in place that checked if state != .complete, but state is a local variable that is not really tracking the write's state, so I decided to replace it with AVAssetWriter.status.

Check points: (check or cross out if not relevant)

• [ ] Added new tests to cover change, if needed
• [X] Build succeeds with all target using Swift Package Manager
• [X] All unit tests pass
• [X] Security oriented best practices and standards are followed (e.g. using input sanitization, principle of least privilege, etc)
• [ ] Documentation update for the change if required
• [X] PR title conforms to conventional commit style
• [ ] If breaking change, documentation/changelog update with migration instructions

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 0% with 1 line in your changes missing coverage. Please review.

Project coverage is 30.48%. Comparing base (da7f9fa) to head (4d96c38). Report is 3 commits behind head on main.

Files	Patch %	Lines
Sources/FaceLiveness/AV/VideoChunker.swift	0.00%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #161 +/- ## ======================================= Coverage 30.48% 30.48% ======================================= Files 57 57 Lines 2227 2227 ======================================= Hits 679 679 Misses 1548 1548 ```

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