test-addons-11/project_timesheet_matrix/models/project_project.py

from odoo import models, fields, api


class ProjectProject(models.Model):
    _inherit = "project.project"

    @api.multi
    def open_timesheets_matrix(self):
        wiz = self.env['project.timesheet.matrix.wiz'].create({})
        return {
            'name': 'Edit timesheets',
            'type': 'ir.actions.act_window',
            'view_type': 'form',
            'view_mode': 'form',
            'res_model': 'project.timesheet.matrix.wiz',
            'target': 'new',
            'res_id': wiz.id,
            'context': self.env.context,
        }