Update release notes

Signed-off-by: Leandro Lucarella <[email protected]>

Author: llucax

RELEASE_NOTES.md

@@ -16,7 +16,7 @@ All upgrading should be done via the migration script or regenerating the templa
 curl -sSL https://raw.githubusercontent.com/frequenz-floss/frequenz-repo-config-python/v0.12/cookiecutter/migrate.py | python3
 ```
 
-But you might still need to adapt your code:
+But you might still need to adapt your code.
 
 <!-- Here upgrade steps for cookiecutter specifically -->
 
@@ -33,6 +33,8 @@ But you might still need to adapt your code:
     * Major updates and dependencies excluded by the above groups are still managed, but they'll create one PR per dependency, as breakage is expected, so it might need manual intervention.
     * Finally, we group some dependencies that are related to each other, and usually needs to be updated together.
 
+- GitHub workflows now use Ubuntu 24.04, as 20.04 is EOL.
+
 ## Bug Fixes
 
 <!-- Here goes notable bug fixes that are worth a special mention or explanation -->