Review Dockerfile

[joao-paulo-parity]

• Use yarn --immutable for installing dependencies (--frozen-lockfile is deprecated)

  substrate-tip-bot/Dockerfile

  Line 13 in 5d55e2c

  RUN yarn install --frozen-lockfile

[mordamax]

@joao-paulo-parity won't existing file work?
https://github.com/paritytech/substrate-tip-bot/blob/master/Dockerfile

[joao-paulo-parity]

@joao-paulo-parity won't existing file work? https://github.com/paritytech/substrate-tip-bot/blob/master/Dockerfile

Yes, although it needs to be reviewed so I'll repurpose this issue

[mordamax]

Done in #18