reset artificial timezone when using newlib (#6828)

Author: d-a-v

cores/esp8266/time.cpp

@@ -122,6 +122,7 @@ void configTime(const char* tz, const char* server1, const char* server2, const
     char tzram[strlen_P(tz) + 1];
     memcpy_P(tzram, tz, sizeof(tzram));
     setenv("TZ", tzram, 1/*overwrite*/);
+    sntp_set_timezone_in_seconds(0);
     tzset();
 
     sntp_init();