unit-test-app: increase timer task size

FreeRTOS timer tests use quite a lot of stack, close to the limit on
the ESP32. ESP32-S3 has larger coprocessor save area, so there is less
space left for the actual stack, and the tests fail with a stack
overflow. Increase the stack size to make the tests work reliably.

tools/unit-test-app/sdkconfig.defaults

@@ -26,3 +26,4 @@ CONFIG_SPIRAM_BANKSWITCH_ENABLE=n
 CONFIG_FATFS_ALLOC_PREFER_EXTRAM=y
 CONFIG_UNITY_ENABLE_BACKTRACE_ON_FAIL=y
 CONFIG_ESP_NETIF_TCPIP_ADAPTER_COMPATIBLE_LAYER=n
+CONFIG_FREERTOS_TIMER_TASK_STACK_DEPTH=3000