Bump the stack size of the uart task

With DEBUG build and a consle UART, this would occur early during startup on makerfabs tft7:
```
I (0) cpu_start: Starting scheduler on APP CPU.
I (10) uart: queue free spaces: 20

***ERROR*** A stack overflow in task uart_event_task has been detected.


Backtrace: 0x403786f2:0x3fce9f40 0x403820a9:0x3fce9f60 0x403850da:0x3fce9f80 0x40383a7d:0x3fcea000 0x40382158:0x3fcea030 0x4038214e:0xa5a5a5a5 |<-CORRUPTED
```

Decoded backtrace was not enlightening:
```
0x403786f2: panic_abort at /home/jepler/src/circuitpython/ports/espressif/build-makerfabs_tft7/esp-idf/../../esp-idf/components/esp_system/panic.c:408
0x403820a9: esp_system_abort at /home/jepler/src/circuitpython/ports/espressif/build-makerfabs_tft7/esp-idf/../../esp-idf/components/esp_system/esp_system.c:137
0x403850da: vApplicationStackOverflowHook at /home/jepler/src/circuitpython/ports/espressif/build-makerfabs_tft7/esp-idf/../../esp-idf/components/freertos/port/xtensa/port.c:407
0x40383a7d: vTaskSwitchContext at /home/jepler/src/circuitpython/ports/espressif/build-makerfabs_tft7/esp-idf/../../esp-idf/components/freertos/tasks.c:3505
0x40382158: _frxt_dispatch at /home/jepler/src/circuitpython/ports/espressif/build-makerfabs_tft7/esp-idf/../../esp-idf/components/freertos/port/xtensa/portasm.S:436
0x4038214e: _frxt_int_exit at /home/jepler/src/circuitpython/ports/espressif/build-makerfabs_tft7/esp-idf/../../esp-idf/components/freertos/port/xtensa/portasm.S:231
0x00000000: ?? ??:0
```

Adding an additional 512 bytes of stack allowed CircuitPython to start
successfully.

Author: jepler

ports/espressif/common-hal/busio/UART.c

@@ -175,7 +175,7 @@ void common_hal_busio_uart_construct(busio_uart_obj_t *self,
     xTaskCreatePinnedToCore(
         uart_event_task,
         "uart_event_task",
-        configMINIMAL_STACK_SIZE,
+        configMINIMAL_STACK_SIZE + 512,
         self,
         CONFIG_PTHREAD_TASK_PRIO_DEFAULT,
         &self->event_task,