use "arduino-sht" library for sht3x and sht4x

examples/TestSht/TestSht.ino

@@ -0,0 +1,38 @@
+#include <AirGradient.h>
+
+#if defined(ESP8266)
+AirGradient ag(DIY_BASIC);
+#else
+AirGradient ag(ONE_INDOOR);
+#endif
+
+void failedHandler(String msg);
+
+void setup() {
+  Serial.begin(115200);
+  Serial.println("Hello");
+  Wire.begin(ag.getI2cSdaPin(), ag.getI2cSclPin());
+
+  if (ag.sht.begin(Wire) == false) {
+    failedHandler("SHT3x init failed");
+  }
+}
+
+void loop() {
+  if (ag.sht.measure()) {
+    float hum = ag.sht.getRelativeHumidity();
+    float temp = ag.sht.getTemperature();
+    Serial.printf("Get temperature: %f\r\n", temp);
+    Serial.printf("   Get humidity: %f\r\n", hum);
+  } else {
+    Serial.println("Measure failed");
+  }
+  delay(1000);
+}
+
+void failedHandler(String msg) {
+  while (true) {
+    Serial.println(msg);
+    delay(1000);
+  }
+}