Fixed memory leak in countdown screen, causing a crash within 2 minutes

src/display.cpp

@@ -119,7 +119,6 @@ const char* FormatPercentage(uint8_t percentage)
 {
   char* value = new char[6];
 
-
   itoa(percentage, value, 10);
 
   uint8_t length = strlen(value);

src/screen/countdown.cpp

@@ -14,7 +14,9 @@ inline uint32_t intDivCeil(uint32_t x, uint32_t y)
 
 void CountdownScreen::printRemainingTime()
 {
-  LCDPrintLineCentered(getDisplay(), 1, FormatTime(mLastDisplayed));
+  const char* time = FormatTime(mLastDisplayed);
+  LCDPrintLineCentered(getDisplay(), 1, time);
+  delete[] time;
 }