Python3 -> gen_appbin.py fails to run

[TheChatty]

Using master rev. 09474e6 I can't run make because Pyhton 3.8 fails running gen_appbin.py: File "/var/tmp/esp_iot_sdk_v2.1.0/tools/gen_appbin.py", line 55 print 'file_name cannot be none\n'

When I force make to use Python 2.7 instead it runs.

The above error is prevalent in that script (missing brackets).