Fix a missing model_dir=

Author: AngledLuffa

stanza/tests/pipeline/test_pipeline_constituency_processor.py

@@ -60,5 +60,5 @@ def test_sorted_two_batch(foundation_cache):
     check_results(doc)
 
 def test_get_constituents(foundation_cache):
-    pipe = stanza.Pipeline("en", processors="tokenize,pos,constituency", foundation_cache=foundation_cache, download_method=None)
+    pipe = stanza.Pipeline("en", model_dir=TEST_MODELS_DIR, processors="tokenize,pos,constituency", foundation_cache=foundation_cache, download_method=None)
     assert "SBAR" in pipe.processors["constituency"].get_constituents()