fix: Update CODEOWNERS (#2981)

## Description:

The maintainer team name has changed, but it was still being referenced
under the old name, so I fixed that.


I’m not entirely sure how CODEOWNERS works, but I created the branch in
the upstream repository thinking it might be required for the checks. It
may not actually be necessary.

## Please complete the following:

- [ ] I have added screenshots for all UI updates
- [ ] I process any text displayed to the user through translateText()
and I've added it to the en.json file
- [ ] I have added relevant tests to the test directory
- [x] I confirm I have thoroughly tested these changes and take full
responsibility for any bugs introduced

## Please put your Discord username so you can be contacted if a bug or
regression is found:
aotumuri

CODEOWNERS

@@ -1,4 +1,4 @@
 # https://docs.github.com/en/repositories/managing-your-repositorys-settings-and-features/customizing-your-repository/about-code-owners
-* @openfrontio/review-approver
+* @openfrontio/maintainer
 resources/lang @openfrontio/translation-approver
-resources/lang/en.json @openfrontio/review-approver
+resources/lang/en.json @openfrontio/maintainer