.github: test-spec: extend low-level with scripts/twister/extended/

Add general dependency for LL testing.

Signed-off-by: Piotr Kosycarz <piotr.kosycarz@nordicsemi.no>

Author: nordic-piks

.github/test-spec.yml

@@ -631,6 +631,7 @@
   - "tests/drivers/pwm/**/*"
   - "tests/drivers/sensor/**/*"
   - "tests/drivers/audio/**/*"
+  - "scripts/twister/extended/**/*"
 
 "CI-ps-test":
   - "samples/nrf_rpc/protocols_serialization/**/*"