Disable pylint similarity check for the migration script

The template will always have a lot of similarity to the current
instance of the script.

Signed-off-by: Leandro Lucarella <luca-frequenz@llucax.com>

Author: llucax

.github/cookiecutter-migrate.template.py

@@ -20,7 +20,8 @@
 And remember to follow any manual instructions for each run.
 """  # noqa: E501
 
-# pylint: disable=too-many-lines, too-many-locals, too-many-branches
+# R0801 is similarity detection, as the template is always similar to the current script
+# pylint: disable=too-many-lines, too-many-locals, too-many-branches, R0801
 
 import hashlib
 import json