add test_filesystem to api

Author: vnghia

.github/workflows/api.yml

@@ -50,6 +50,7 @@ jobs:
           python -m pytest -s -v tests/test_s3.py
           python -m pytest -s -v tests/test_azure.py
           python -m pytest -s -v tests/test_gcs.py
+          python -m pytest -s -v tests/test_filesystem.py
 
   linux:
     name: Linux ${{ matrix.python }} + ${{ matrix.version }}
@@ -88,6 +89,7 @@ jobs:
           python -m pytest -s -v tests/test_s3.py
           python -m pytest -s -v tests/test_azure.py
           if [[ "${{ matrix.version }}" != "tf-nightly:tensorflow-io" ]]; then python -m pytest -s -v tests/test_gcs.py ; fi
+          python -m pytest -s -v tests/test_filesystem.py
 
   windows:
     name: Windows ${{ matrix.python }} + ${{ matrix.version }}