Change lowercase detection to work with CJK languages

str.islower() does not properly work with characters in the Lo category
so CJK languages fail the check.

Fix #7698

discord/app_commands/commands.py

@@ -142,7 +142,12 @@ def validate_name(name: str) -> str:
     match = VALID_SLASH_COMMAND_NAME.match(name)
     if match is None:
         raise ValueError('names must be between 1-32 characters')
-    if not name.islower():
+
+    # Ideally, name.islower() would work instead but since certain characters
+    # are Lo (e.g. CJK) those don't pass the test. I'd use `casefold` instead as
+    # well, but chances are the server-side check is probably something similar to
+    # this code anyway.
+    if name.lower() != name:
         raise ValueError('names must be all lower case')
     return name