Small change, very minor

[dherkes]

Recent versions of the esptool program are warning about the impending removal of the .py extension. For example when I flash using:

"esptool.py --port /dev/ttyUSB0 write_flash -fs 4MB -ff 80m -fm dio 0x00000 firmware/0x00000.bin 0x02000 firmware/0x02000.bin"

two error messages are generated.

By changing the command to:

"esptool --port /dev/ttyUSB0 write-flash -fs 4MB -ff 80m -fm dio 0x00000 firmware/0x00000.bin 0x02000 firmware/0x02000.bin"

the error message no longer are generated. I have used this code for years, and appreciate your efforts.