fix: add future annotations to xml_utils and fix stale body_name key in tests

Author: TATP-233

src/unilab/utils/xml_utils.py

@@ -1,3 +1,5 @@
+from __future__ import annotations
+
 import os
 import tempfile
 import xml.etree.ElementTree as ET

tests/base/test_sim_backend.py

@@ -406,7 +406,7 @@ def test_get_sensor_data_b_shape(self, bkd, body_ids):
 
     def test_base_body_pos_b_is_zero(self, bkd):
         """Base body position relative to itself must be [0,0,0]."""
-        pelvis_id = bkd.model.get_body_index(_G1["body_name"])
+        pelvis_id = bkd.model.get_body_index(_G1["base_name"])
         pos_b = bkd.get_body_pos_b(np.array([pelvis_id]))
         np.testing.assert_allclose(pos_b, 0.0, atol=1e-4)