Address CoPilot suggestions

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Author: ezilber-akamai

linode_api4/util.py

@@ -30,7 +30,7 @@ def recursive_helper(value: Any) -> Any:
     return recursive_helper(data)
 
 
-def generate_device_suffixes(n):
+def generate_device_suffixes(n: int) -> list[str]:
     """
     Generate n alphabetical suffixes starting with a, b, c, etc.
     After z, continue with aa, ab, ac, etc. followed by aaa, aab, etc.