[CI] Version-pin trimesh to 3.16.0

See mikedh/trimesh#1772

Author: stephane-caron

tox.ini

@@ -73,6 +73,7 @@ commands =
 [testenv:loader-yourdfpy]
 deps =
     pytest
+    trimesh ~=3.16.0
     yourdfpy >=0.0.52
 commands =
     pytest --import-mode=importlib tests/loaders/test_yourdfpy.py