Fix delete task with evidences 5xx

close #64

Signed-off-by: gearnode <bryan@frimin.fr>

pkg/coredata/migrations/20250327T065928Z.sql

@@ -0,0 +1,9 @@
+ALTER TABLE evidences DROP CONSTRAINT evidences_task_id_fkey;
+
+ALTER TABLE evidences
+  ADD CONSTRAINT evidences_task_id_fkey
+  FOREIGN KEY (task_id)
+  REFERENCES tasks(id)
+  ON DELETE SET NULL;
+
+ALTER TABLE evidences ALTER COLUMN task_id DROP NOT NULL;