[STYLE] Apply Black formatting to Python files

Applied Black code formatter to maintain consistent code style:

- Reformatted _version.py
- Reformatted cheques_tests.py
- Reformatted estadisticas_cambiarias_tests.py

No functional changes, only code style adjustments.

src/bcra_connector/_version.py

@@ -1,4 +1,4 @@
 # This file is auto-generated by Hatchling. As such, do not:
 #   - modify
 #   - track in version control e.g. be sure to add to .gitignore
-__version__ = VERSION = '0.3.3'
+__version__ = VERSION = "0.3.3"

tests/cheques_tests.py

@@ -12,7 +12,6 @@
 
 
 class TestCheques(unittest.TestCase):
-
     def test_entidad(self):
         data = {"codigoEntidad": 11, "denominacion": "BANCO DE LA NACION ARGENTINA"}
         entidad = Entidad.from_dict(data)

tests/estadisticas_cambiarias_tests.py

@@ -15,7 +15,6 @@
 
 
 class TestEstadisticasCambiarias(unittest.TestCase):
-
     def test_divisa(self):
         data = {"codigo": "USD", "denominacion": "DOLAR ESTADOUNIDENSE"}
         divisa = Divisa.from_dict(data)