core system: Fix warnings in compilation when assertions are disabled

Adds a CI config for hello world that sets this, to catch future regressions

components/esp_adc_cal/esp_adc_cal_esp32s2.c

@@ -177,7 +177,7 @@ esp_adc_cal_value_t esp_adc_cal_characterize(adc_unit_t adc_num,
         uint32_t default_vref,
         esp_adc_cal_characteristics_t *chars)
 {
-    bool res;
+    bool res __attribute__((unused));
     adc_calib_parsed_info efuse_parsed_data = {0};
     // Check parameters
     assert((adc_num == ADC_UNIT_1) || (adc_num == ADC_UNIT_2));