launcher: verify updates against GitHub and check release dates (#482)

* launcher: verify with GitHub when website feed differs and compare tag dates

* launcher: restore kyty_emulator dependency for CI build and install

* launcher: simplify GitHub update verification

---------

Co-authored-by: nmzik <Nmzik@mail.ru>

src/launcher/src/updateChecker.cpp

@@ -84,7 +84,8 @@ void UpdateChecker::FetchUpdateInfo(const char* url, bool fallback, bool manual)
 		}
 		reply->deleteLater();
 
-		if (!info.error.isEmpty() && !fallback) {
+		if (!fallback &&
+		    (!info.error.isEmpty() || info.tag != QString::fromLatin1(KYTY_RELEASE_TAG))) {
 			FetchUpdateInfo(FALLBACK_FEED_URL, true, manual);
 			return;
 		}