[ci] Add the deadsnakes PPA.
[ci] Add the deadsnakes PPA.

I was wrong...

crr0004/lime,farhaanbukhsh/lime,crr0004/lime,crr0004/lime,farhaanbukhsh/lime,farhaanbukhsh/lime,farhaanbukhsh/lime,farhaanbukhsh/lime,crr0004/lime,crr0004/lime