Fix copyWorkplane (#1770)

* Fix copyWorkplane

* Back to T

---------

Co-authored-by: AU <[email protected]>

Author: bfleischhacker

cadquery/cq.py

@@ -664,7 +664,7 @@ def copyWorkplane(self, obj: T) -> T:
         :type obj: a CQ object
         :returns: a CQ object with obj's workplane
         """
-        out = obj.__class__(obj.plane)
+        out = copy(obj)
         out.parent = self
         out.ctx = self.ctx
         return out