MAINTAINERS: remove sir-branch

sir-branch hasn't reviewed any PRs or engaged in any Zephyr
activity since July 2022.

Recent activities:

- issue: JSON parses uses recursion (breaks rule 17.2)
  #48102
  (2022-07-21T08:41:09Z)
- review: Review on 'json: Skip unknown fields on parsing'
  #47989
  (2022-07-21T05:22:37Z)
- pr: net: sockets_tls: Reset mbedtls session on handshake errors
  #41527
  (2022-01-01T23:17:25Z)

Signed-off-by: Benjamin Cabé <[email protected]>

Author: kartben

MAINTAINERS.yml

@@ -2963,7 +2963,6 @@ JSON Web Token:
     - d3zd3z
   collaborators:
     - mrfuchs
-    - sir-branch
   files:
     - subsys/jwt/
     - include/zephyr/data/json.h