fix: load test config in grants test

- Add config_test.yaml loading to test_build_grants_with_default_config
- Fix FileNotFoundError when config.yaml is not available in CI
- Ensure test uses config_test.yaml instead of missing config.yaml

tests/test_citation_builder.py

@@ -216,6 +216,14 @@ def test_process_author_edge_cases(pi_finder):
 
 def test_build_grants_with_default_config(pi_finder):
     """Test that grants include default grants from config"""
+    import os
+
+    from doi2dataset import Config
+
+    # Load test config
+    config_path = os.path.join(os.path.dirname(__file__), "config_test.yaml")
+    Config.load_config(config_path=config_path)
+
     # Use real data structure but focus on grants behavior
     data = {"authorships": [], "grants": []}