Removing stupid snprintf warnings

ampel-firmware/src/lib/NTPClient/NTPClient.cpp

@@ -227,7 +227,8 @@ void NTPClient::getFormattedTime(char *formatted_time, unsigned long secs) {
 // Based on https://github.com/PaulStoffregen/Time/blob/master/Time.cpp
 void NTPClient::getFormattedDate(char *formatted_date, unsigned long secs) {
   unsigned long rawTime = (secs ? secs : this->getEpochTime()) / 86400L;  // in days
-  unsigned long days = 0, year = 1970;
+  unsigned long days = 0;
+  unsigned int year = 1970;
   uint8_t month;
   static const uint8_t monthDays[]={31,28,31,30,31,30,31,31,30,31,30,31};
 
@@ -250,7 +251,7 @@ void NTPClient::getFormattedDate(char *formatted_date, unsigned long secs) {
 
   char formatted_time[9];
   this->getFormattedTime(formatted_time, secs);
-  snprintf(formatted_date, 23, "%4lu-%02d-%02lu %s%+03d", year, month, rawTime, formatted_time, this->_timeOffset / 3600);
+  snprintf(formatted_date, 23, "%4d-%02d-%02lu %s%+03d", year, month, rawTime, formatted_time, (int8_t) this->_timeOffset / 3600);
 }
 
 void NTPClient::setEpochTime(unsigned long secs) {