tools/spec: use preferred 'not in' syntax for PEP8

tools/spec.py

@@ -326,7 +326,7 @@ class POD(Type):
             n = member.find('name').text
 
             comment = member.find('comment')
-            if not comment is None:
+            if comment is not None:
                 member.remove(comment)
             code = " ".join(member.itertext())
 
@@ -498,7 +498,7 @@ class Require(object):
                 required.append(name)
                 continue
 
-            if not 'extends' in value.attrib:
+            if 'extends' not in value.attrib:
                 obj = Constant(value)
                 owner = reg.types['API Constants']
                 owner.values.append(obj)