Merge branch 'feature/esptool_v2.8_v3.1' into 'release/v3.1'

esptool: Bump to v2.8 release (v3.1)

See merge request espressif/esp-idf!6463
This commit is contained in:
Jiang Jiang Jian
2019-10-25 11:35:22 +08:00