advertise pv=1.1 (HAP R2) in mDNS

Experiment: bump the protocol-version TXT record from 1.0 (HAP R1)
to 1.1 (HAP R2, what every modern HK accessory advertises). The
underlying lib still implements R1 semantics; this is purely a
metadata change to see whether iOS Home's automation editor changes
how it renders our HeaterCooler accessory's preview tile (it
currently shows CurrentTemperature.min_value as a placeholder
instead of the live value).

Author: naanlizard

src/arduino_homekit_server.cpp

@@ -3241,7 +3241,13 @@ void homekit_mdns_init(homekit_server_t *server) {
 			}
 	);
 	MDNS.addServiceTxt(mdns_service, "md", model->value.string_value);
-	MDNS.addServiceTxt(mdns_service, "pv", "1.0");
+	// HAP R2 (2018+) protocol version. Most modern HK accessories advertise
+	// pv=1.1. The Mixiaoxiao lib was originally HAP R1; we advertise 1.1 to
+	// see if iOS Home's automation editor renders the device tile differently
+	// (it falls back to CurrentTemperature.min_value when it can't read what
+	// it expects — possibly TargetTemperature, which the HeaterCooler service
+	// doesn't include).
+	MDNS.addServiceTxt(mdns_service, "pv", "1.1");
 	MDNS.addServiceTxt(mdns_service, "id", server->accessory_id);
 	//"c#" is a DynamicServiceTxt
 	//Current configuration number. Required.