Fix: prevent to add lib dir multiple times to python path

src/jflow/component.py

@@ -575,7 +575,9 @@ class Component(object):
                              add_path=list(), collect=False, local=False, map=False, cmd_format=""):
 
         workflow_dir = Path(os.path.dirname(inspect.getfile(self.__class__))).parent
-        add_path.append(str(workflow_dir) + os.path.sep + "lib")
+        lib_dir = str(workflow_dir) + os.path.sep + "lib"
+        if not lib_dir in add_path:
+            add_path.append(lib_dir)
                
         if map:
             if not issubclass(inputs.__class__, list) or not issubclass(outputs.__class__, list):