BIM: remove obsolete Python 2 urllib2 import

Python 3 combined the former `urllib`, `urllib2`, `urlparse` Python 2 modules into subpackages of `urllib`. FreeCAD is written in Python 3, thus the `urllib2` import fallback will not work and needs to be removed.

src/Mod/BIM/ArchCommands.py

@@ -759,10 +759,7 @@ def download(url, force=False):
     """download(url,force=False): downloads a file from the given URL and saves it in the
     macro path. Returns the path to the saved file. If force is True, the file will be
     downloaded again evn if it already exists."""
-    try:
-        from urllib.request import urlopen
-    except ImportError:
-        from urllib2 import urlopen
+    from urllib.request import urlopen
     import os
 
     name = url.split("/")[-1]