add tests

.gitlab-ci.yml

src/easymatcher_worker.py

tests/__init__.py

tests/example_data/expected/document.jsonl

tests/example_data/expected/document1.jsonl

tests/example_data/expected/document2.jsonl

tests/example_data/expected/documents.jsonl

tests/example_data/input/document2.txt

tests/example_data/input/labels.json

tests/example_data/output/.gitkeep

tests/fixtures/example_data.py

tests/utils.py

tests/worker/test_worker.py