Allow ordering of all columns but most_recent

most_recent is a Review object and it's not obvious what about that
column would be orderable.

hypha/apply/funds/tables.py

@@ -365,6 +365,7 @@ class RoundsFilter(filters.FilterSet):
 
 class LeaderboardTable(tables.Table):
     full_name = tables.Column(verbose_name="Reviewer")
+    most_recent = tables.Column(orderable=False)
 
     class Meta:
         fields = [
@@ -376,7 +377,6 @@ class LeaderboardTable(tables.Table):
             'most_recent',
         ]
         model = User
-        orderable = False
 
     def render_most_recent(self, record):
         review = (Review.objects.filter(author__reviewer=record)