MAINTAINERS: SMF: add @vlad-kulikov as collaborator

I nominate my self as s collaborator for the State machine framework (SMF).
Rationale: sustained contributions to SMF (performance work, tests,
reviews).

@keith-zephyr @glenn-andrews - PTAL.

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

Author: vlad-kulikov

MAINTAINERS.yml

@@ -4747,6 +4747,7 @@ State machine framework:
   collaborators:
     - keith-zephyr
     - glenn-andrews
+    - vlad-kulikov
   files:
     - doc/services/smf/
     - include/zephyr/smf.h