Fix backup restore

This merge request fixes the backup restore system.

Note that it might not be backward compatible.

Fixes #492

beat/web/experiments/models/block.py

@@ -138,6 +138,7 @@ class Block(models.Model):
             self.experiment.toolchain.version,
             self.experiment.name,
         )
+    natural_key.dependencies = ['experiments.experiment']
 
 
     def save(self, *args, **kwargs):