style: remove black

Makefile

@@ -28,21 +28,19 @@ build: clean deps
 format:
 	@# Do not analyse .gitignored files.
 	@# `make` needs `$$` to output `$`. Ref: http://stackoverflow.com/questions/2382764.
-	black `git ls-files | grep "\.py$$"`
+	ruff format `git ls-files | grep "\.py$$"`
 	isort `git ls-files | grep "\.py$$"`
 	pyproject-fmt pyproject.toml
-	ruff format `git ls-files | grep "\.py$$"`
 
 lint:
 	@# Do not analyse .gitignored files.
 	@# `make` needs `$$` to output `$`. Ref: http://stackoverflow.com/questions/2382764.
-	black --check `git ls-files | grep "\.py$$"`
 	isort --check `git ls-files | grep "\.py$$"`
 	ruff check `git ls-files | grep "\.py$$"`
 	yamllint `git ls-files | grep "\.yaml$$"`
 
 test: clean
-	PYTEST_ADDOPTS="--import-mode importlib" openfisca test --country-package openfisca_country_template openfisca_country_template/tests
+	openfisca test --country-package openfisca_country_template openfisca_country_template/tests
 
 serve-local: build
 	openfisca serve --country-package openfisca_country_template

pyproject.toml

@@ -27,7 +27,6 @@ dependencies = [
     "openfisca-core[web-api]>=43",
 ]
 optional-dependencies.dev = [
-    "black>=24.8,<25",
     "isort>=5.13.2,<6",
     "pyproject-fmt>=2.3.1,<3",
     "ruff>=0.6.9,<1",
@@ -40,9 +39,6 @@ urls.Homepage = "https://github.com/openfisca/country-template"
 urls.Issues = "https://github.com/openfisca/country-template/issues"
 urls.Repository = "https://github.com/openfisca/country-template"
 
-[tool.black]
-target_version = [ "py39", "py310", "py311" ]
-
 [tool.ruff]
 target-version = "py39"
 format.docstring-code-line-length = 72
@@ -97,7 +93,7 @@ indent = 4
 max_supported_python = "3.11"
 
 [tool.pytest.ini_options]
-addopts = "--exitfirst --showlocals --doctest-modules --disable-warnings"
+addopts = "--exitfirst --showlocals --doctest-modules --disable-warnings --import-mode importlib"
 testpaths = [ "openfisca_country_template/tests" ]
 python_files = "**/*.py"