MAINTAINERS: Add babrsn to Bluetooth Audio

I have contributed the following PRs:
https://github.com/zephyrproject-rtos/zephyr/pull/80000
https://github.com/zephyrproject-rtos/zephyr/pull/79360
https://github.com/zephyrproject-rtos/zephyr/pull/78846
https://github.com/zephyrproject-rtos/zephyr/pull/78751
https://github.com/zephyrproject-rtos/zephyr/pull/74950
https://github.com/zephyrproject-rtos/zephyr/pull/74946
https://github.com/zephyrproject-rtos/zephyr/pull/73845
https://github.com/zephyrproject-rtos/zephyr/pull/72849



and am attending the weekly LE Audio Zephyr meetings.

Signed-off-by: Babak Arisian <bbaa@demant.com>