According document of 'What’s New In Python 3.7', 'async' are reserved keywords now.

Code in line 105 of 'odoo/addons/base/ir/ir_qweb/assetsbundle.py' 
`def to_html(self, sep=None, css=True, js=True, debug=False, async=False, url_for=(lambda url: url)):`
will throw SyntaxError out if we launch odoo with this update python.
atype = 'text/javascript'
                    path = [segment for segment in href.split('/') if segment]
                    filename = get_resource_path(*path) if path else None
                    files.append({'atype': atype, 'url': src, 'filename': filename, 'content': el.text, 'media': media})
                else:
                    remains.append((el.tag, OrderedDict(el.attrib), el.text))
            else:
                
                pass
        return (files, remains)
    def _get_field(self, record, field_name, expression, tagName, field_options, options, values):
        field = record._fields[field_name]
        
        field_options['template_options'] = options
        
        field_options['tagName'] = tagName
        field_options['expression'] = expression
        field_options['type'] = field_options.get('widget', field.type)
        inherit_branding = options.get('inherit_branding', options.get('inherit_branding_auto') and record.check_access_rights('write', False))
        field_options['inherit_branding'] = inherit_branding
        translate = options.get('edit_translations') and options.get('translatable') and field.translate
        field_options['translate'] = translate
        
        model = 'ir.qweb.field.' + field_options['type']
        converter = self.env[model] if model in self.env else self.env['ir.qweb.field']
        
        content = converter.record_to_html(record, field_name, field_options)
        attributes = converter.attributes(record, field_name, field_options, values)
        return (attributes, content, inherit_branding or translate)
    def _get_widget(self, value, expression, tagName, field_options, options, values):