test: test_cancel_absence an neue 200-Response angepasst (vorher 204)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/tests/test_absences.py

@@ -240,7 +240,8 @@ async def test_cancel_absence(client: AsyncClient, abs_headers, vacation_type_id
     absence_id = create_resp.json()["id"]
 
     resp = await client.delete(f"/api/v1/absences/{absence_id}", headers=abs_headers)
-    assert resp.status_code == 204
+    assert resp.status_code == 200
+    assert resp.json()["status"] == "cancelled"
 
 
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