[FIX] energy_project: add project_id to contract model

energy_project/models/__init__.py

@@ -3,3 +3,4 @@ from . import project_type
 from . import inscription
 from . import reseller
 from . import supplier
+from . import contract

energy_project/models/contract.py

+from odoo import fields, models
+
+
+class Contract(models.Model):
+    _inherit = "contract.contract"
+
+    project_id = fields.Many2one(
+        "energy_project.project",
+        required=True,
+        ondelete="restrict",
+        string="Energy Project",
+        check_company=True,
+    )