Update flash-firmware-usb.py

Author: DominikN

rosbot_utils/rosbot_utils/flash-firmware-usb.py

@@ -65,6 +65,7 @@ def try_flash_operation(self, operation_name, flash_command, flash_args):
             try:
                 self.enter_bootloader_mode()
                 sh.usbreset("0403:6015")
+                time.sleep(2.0)
                 flash_command(self.port, *flash_args, _out=sys.stdout)
                 self.exit_bootloader_mode()
                 time.sleep(0.2)