fix: remove non-existent --extra s3 from CI workflow

The pyproject.toml only defines a 'test' extra group. S3 artifact
tests already use pytest.importorskip('aioboto3') to gracefully skip
when the dependency is not installed.

Author: miyannishar

.github/workflows/unit-tests.yaml

@@ -31,7 +31,7 @@ jobs:
           uv venv .venv
           source .venv/bin/activate
           # Install dependencies as recommended in CONTRIBUTING.md
-          uv sync --extra test --extra s3
+          uv sync --extra test
 
       - name: Run unit tests with pytest
         run: |