I think another option is to just let it go and you can "fix" it later if you want and have the chance. Just put it in a "cleanup" commit or something. Don't be passive agressive about it, make it a team practice. Sometimes people will change the style of your code, that's ok, it's not a slight against you.
However, if you get in a situation where people are changing styles back and forth then you need to talk it out. E.g. Alice inserts a blank line, Bob removes the blank line, Alice inserts the blank line again - time to talk about blank lines and code style.
In this case, if Alice sorts the dictionary keys and Bob couldn't care less, it seems both can have what they want by simply letting Alice sort the keys. And if it becomes a common thing instead of a one-off, maybe talk about it.
