Update conf.py (#5518)
Update conf.py (#5518)

version bump to 2.5.0-beta2
Lan-Hekary/Arduino,esp8266/Arduino,esp8266/Arduino,Lan-Hekary/Arduino,Lan-Hekary/Arduino,sticilface/Arduino,esp8266/Arduino,sticilface/Arduino,sticilface/Arduino,Lan-Hekary/Arduino,Lan-Hekary/Arduino,sticilface/Arduino,esp8266/Arduino,sticilface/Arduino,esp8266/Arduino