filter-repo: Use extra LF on progress messages

Extra LFs are permitted in git-fast-import syntax, and they serve to
make it easier to read the stream (from --dry-run or --debug), if they
are so inclined.

Signed-off-by: Elijah Newren <newren@gmail.com>

git-filter-repo

@@ -732,7 +732,7 @@ class Progress(_GitElement):
     self.dumped = 1
 
     file_.write('progress %s\n' % self.message)
-    #file_.write('\n')
+    file_.write('\n')
 
 class Checkpoint(_GitElement):
   """