Migrate to python 3

bom.py

@@ -5,9 +5,8 @@ from trytond.pool import PoolMeta
 __all__ = ['BOM', 'BOMDrawingLine']
 
 
-class BOM:
+class BOM(metaclass=PoolMeta):
     __name__ = 'production.bom'
-    __metaclass__ = PoolMeta
     drawing = fields.Many2One('production.drawing', 'Drawing',
         ondelete='RESTRICT')
     drawing_lines = fields.One2Many('production.bom.drawing.line',

production.py

@@ -5,9 +5,8 @@ from trytond.pool import PoolMeta, Pool
 __all__ = ['Production', 'ProductionDrawingLine']
 
 
-class Production:
+class Production(metaclass=PoolMeta):
     __name__ = 'production'
-    __metaclass__ = PoolMeta
     drawing = fields.Many2One('production.drawing', 'Drawing',
         ondelete='RESTRICT', states={
             'readonly': True,

setup.py

@@ -5,10 +5,7 @@ from setuptools import setup
 import re
 import os
 import io
-try:
-    from configparser import ConfigParser
-except ImportError:
-    from ConfigParser import ConfigParser
+from configparser import ConfigParser
 
 MODULE = 'production_drawing'
 PREFIX = 'nantic'