skip pyparsing 3.x on py3.6

Author: mr-c

requirements.txt

@@ -12,3 +12,4 @@ coloredlogs
 pydot>=1.4.1
 argcomplete>=1.12.0
 pyparsing != 3.0.2  # breaks --print-dot (pydot) https://github.com/pyparsing/pyparsing/issues/319
+pyparsing < 3;python_version<='3.6'  # breaks --print-dot

setup.py

@@ -122,6 +122,7 @@
         "coloredlogs",
         "pydot >= 1.4.1",
         "pyparsing != 3.0.2",  # breaks --print-dot (pydot) https://github.com/pyparsing/pyparsing/issues/319
+        "pyparsing < 3 ;python_version<='3.6'",  # breaks --print-dot (pydot)
         "argcomplete",
     ],
     extras_require={

tests/test_examples.py

@@ -1036,7 +1036,7 @@ def test_print_dot() -> None:
         )
     )[0]
     stdout = StringIO()
-    assert main(["--print-dot", cwl_path], stdout=stdout) == 0
+    assert main(["--debug", "--print-dot", cwl_path], stdout=stdout) == 0
     computed_dot = pydot.graph_from_dot_data(stdout.getvalue())[0]
     computed_edges = sorted(
         (urlparse(source).fragment, urlparse(target).fragment)