doc: remove has_key usage in hgmanpage

doc/hgmanpage.py

@@ -303,7 +303,7 b' class Translator(nodes.NodeVisitor):'
 
             def __init__(self, style):
                 self._style = style
-                if node.has_key('start'):
+                if 'start' in node:
                     self._cnt = node['start'] - 1
                 else:
                     self._cnt = 0
@@ -345,7 +345,7 b' class Translator(nodes.NodeVisitor):'
             def __repr__(self):
                 return 'enum_style-%s' % list(self._style)
 
-        if node.has_key('enumtype'):
+        if 'enumtype' in node:
             self._list_char.append(enum_char(node['enumtype']))
         else:
             self._list_char.append(enum_char('bullet'))