[doc] Add missing space in urllib.request.rst (pythonGH-19860)

This is just a typo fix, should I still provide news file?

Doc/library/urllib.request.rst

@@ -1235,7 +1235,7 @@ Here is an example of doing a ``PUT`` request using :class:`Request`::
 
     import urllib.request
     DATA = b'some data'
-    req = urllib.request.Request(url='http://localhost:8080', data=DATA,method='PUT')
+    req = urllib.request.Request(url='http://localhost:8080', data=DATA, method='PUT')
     with urllib.request.urlopen(req) as f:
         pass
     print(f.status)