Removed literal '\n' in ESP8266HTTPUpdateServer response (#3421)

Author: hchahine

libraries/ESP8266HTTPUpdateServer/src/ESP8266HTTPUpdateServer.cpp

@@ -12,7 +12,7 @@ static const char serverIndex[] PROGMEM =
                   <input type='file' name='update'>
                   <input type='submit' value='Update'>
                </form>
-         </body></html>\n)";
+         </body></html>)";
 static const char successResponse[] PROGMEM = 
   "<META http-equiv=\"refresh\" content=\"15;URL=\">Update Success! Rebooting...\n";