docs: Use curl -f and python -I to run the migration script

This is to improve resilience and security.

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

Author: llucax

.github/cookiecutter-migrate.template.py

@@ -10,7 +10,7 @@
 
 To run it, the simplest way is to fetch it from GitHub and run it directly:
 
-    curl -sSL https://raw.githubusercontent.com/frequenz-floss/frequenz-repo-config-python/<tag>/cookiecutter/migrate.py | python3
+    curl -sSLf https://raw.githubusercontent.com/frequenz-floss/frequenz-repo-config-python/<tag>/cookiecutter/migrate.py | python3
 
 Make sure to replace the `<tag>` to the version you want to migrate to in the URL.
 

RELEASE_NOTES.md

@@ -13,7 +13,7 @@
 All upgrading should be done via the migration script or regenerating the templates.
 
 ```bash
-curl -sSL https://raw.githubusercontent.com/frequenz-floss/frequenz-repo-config-python/<tag>/cookiecutter/migrate.py | python3
+curl -sSLf https://raw.githubusercontent.com/frequenz-floss/frequenz-repo-config-python/<tag>/cookiecutter/migrate.py | python3 -I
 ```
 
 But you might still need to adapt your code:

cookiecutter/migrate.py

@@ -10,7 +10,7 @@
 
 To run it, the simplest way is to fetch it from GitHub and run it directly:
 
-    curl -sSL https://raw.githubusercontent.com/frequenz-floss/frequenz-repo-config-python/<tag>/cookiecutter/migrate.py | python3
+    curl -sSLf https://raw.githubusercontent.com/frequenz-floss/frequenz-repo-config-python/<tag>/cookiecutter/migrate.py | python3 -I
 
 Make sure to replace the `<tag>` to the version you want to migrate to in the URL.
 

docs/user-guide/update-to-a-new-version.md

@@ -115,8 +115,8 @@ The script can also only migrate from one version to the next. If you are
 skipping versions, you will have to run the script multiple times.
 
 ```sh
-curl -sSL https://raw.githubusercontent.com/frequenz-floss/frequenz-repo-config-python/{{ ref_name }}/cookiecutter/migrate.py \
-	| python3
+curl -sSLf https://raw.githubusercontent.com/frequenz-floss/frequenz-repo-config-python/{{ ref_name }}/cookiecutter/migrate.py \
+	| python3 -I
 ```
 
 Make sure that the version (`{{ ref_name }}`) matches the