MAINTAINERS: add vlad-kulikov as SMF maintainer

This is a follow-up to @keith-zephyr’s note that SMF is looking for a
new maintainer:
#97943 (comment)

I am proposing this shortly after getting collaborator only
because there is an active search and I am already working in SMF
(source-level changes, SMF-related RFCs, and improving the
sibling-transition path to make the common transition at least
~30% faster). If there were no open need, I would have waited longer
before proposing this.

Signed-off-by: Vladislav Kulikov <vlad_kulikov_c@pm.me>

Author: vlad-kulikov

MAINTAINERS.yml

@@ -4744,10 +4744,10 @@ State machine framework:
   status: maintained
   maintainers:
     - sambhurst
+    - vlad-kulikov
   collaborators:
     - keith-zephyr
     - glenn-andrews
-    - vlad-kulikov
   files:
     - doc/services/smf/
     - include/zephyr/smf.h