MAINTAINERS: add jbehrensnx as collaborator in stepper driver subsystem

In regards to the contributions to stepper driver subsystem, i would like
to propose Jan Behrens as collaborator in stepper driver subsystem

Signed-off-by: Jilay Pandya <[email protected]>

Author: jilaypandya

MAINTAINERS.yml

@@ -2111,6 +2111,7 @@ Release Notes:
     - dipakgmx
     - fabiobaltieri
     - faxe1008
+    - jbehrensnx
   files:
     - drivers/stepper/
     - include/zephyr/drivers/stepper.h