chore: update tests to adaped to new structure

tests/test_smard.py

@@ -0,0 +1,20 @@
+import polars as pl
+import requests_mock
+from collectors.smard import fetch_smard_data
+
+def test_fetch_smard_data():
+    with requests_mock.Mocker() as m:
+        # Mock index call
+        m.get("https://www.smard.de/app/chart_data/4169/DE-LU/index_hour.json", 
+              json={"timestamps": [1700000000000]})
+        # Mock data call
+        m.get("https://www.smard.de/app/chart_data/4169/DE-LU/4169_DE-LU_hour_1700000000000.json", 
+              json={
+                  "series": [[1700000000000, 50.0], [1700003600000, 60.0]]
+              })
+        
+        df = fetch_smard_data(filter_id=4169)
+        assert isinstance(df, pl.DataFrame)
+        assert df.shape == (2, 2)
+        assert "value" in df.columns
+        assert df["value"][0] == 50.0