Increased coverage to 90%

Wrote new unit tests during refactoring, coverage can be increased.
Put the configuration in pyproject.toml, so everyone can run it with
the same configuration.

.github/workflows/tests.yml

@@ -37,5 +37,4 @@ jobs:
         run: git lfs pull
 
       - name: Run pytest
-        # TODO: Dummy coverage (branch: 0%) is needed for the pass rate. Increase this
-        run: poetry run pytest --cov=. --cov-branch --cov-fail-under=0
+        run: poetry run pytest

pyproject.toml

@@ -32,6 +32,9 @@ profile = "black"
 [tool.poetry.scripts]
 unblob = "unblob.cli:main"
 
+[tool.pytest.ini_options]
+addopts = "--cov=. --cov-branch --cov-fail-under=90"
+
 [build-system]
 requires = ["poetry-core>=1.0.0"]
 build-backend = "poetry.core.masonry.api"