Fix typo in warning message about type checking

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>
Signed-off-by: Leandro Lucarella <luca-frequenz@llucax.com>

Author: llucax

src/frequenz/core/warnings/_deprecated_aliases.py

@@ -80,7 +80,7 @@ def deprecated_aliases(  # noqa: DOC502
     Danger:
         Follow the usage example structure strictly. In particular never drop
         the `else:`, otherwise a type checker will see the `__getattr__`
-        assignement and treat every symbol in the module as [`Any`][typing.Any],
+        assignment and treat every symbol in the module as [`Any`][typing.Any],
         effectively disabling type checking for the entire module.
 
     Example: Usage