old_contents: ##############################################################################
  # For copyright and license notices, see __manifest__.py file in module root
  # directory
  ##############################################################################
  from odoo import models, fields
  
  
  class ProjectProject(models.Model):
  
      _inherit = 'project.project'
      _order = "sequence"
  
      stage_id = fields.Many2one(
          'project.stage',
          'Stage',
          track_visibility='onchange',
          index=True,
          copy=False,
      )
      kanban_state = fields.Selection(
          [('normal', 'In Progress'),
           ('blocked', 'Blocked'),
           ('done', 'Ready for next stage')],
          track_visibility='onchange',
          help="A task's kanban state indicates special "
               "situations affecting it:\n"
          " * Normal is the default situation\n"
          " * Blocked indicates something is preventing "
               "the progress of this task\n"
          " * Ready for next stage indicates the task is ready "
               "to be pulled to the next stage",
          required=False,
          copy=False,
      )
  
new_contents: ##############################################################################
  # For copyright and license notices, see __manifest__.py file in module root
  # directory
  ##############################################################################
  from odoo import models, fields
  
  
  class ProjectProject(models.Model):
  
      _inherit = 'project.project'
      _order = "sequence"
  
      stage_id = fields.Many2one(
          'project.stage',
          'Stage',
          track_visibility='onchange',
          index=True,
          copy=False,
      )
  
subject: remove unused field "kanban_state"