update to sha256 for checksum verification

[perobertson]

This is based on top of https://github.com/factoriotools/factorio-docker/pull/403

The second commit switches from sha1 to sha256 as the checksum verification.

Why switch

sha1 is a smaller size so it is more susceptible to collision attacks. Since this check is only being done once during the image build, the end users will not see any difference.

• https://www.howtogeek.com/238705/what-is-sha-1-and-why-will-retiring-it-kick-thousands-off-the-internet/
• https://shattered.io/

[Fank]

Can you make this change based on #382 ? The checksum handling is still sha1 but a little bit different

[perobertson]

Sounds good to me. Ill close this one and open up a new PR since the changes there are significant.

That will be a nice update for this repo. This project has been quite handy. Thanks to everyone involved in getting this put together.

[Fank]

PR is merged