Improve and clarify the dev setup process on a new machine

[ekurutepe]

Checklist

• If applicable, unit tests
• If applicable, create follow-up issues for purchases-android and hybrids

Motivation

I ran into a few issues while setting up my new Mac. I'm sure I'm not the only and these initial setup issues are super frustrating.

Description

• add Sequoia to the supported platforms
• specify a ruby version for the gemfile
• add the need to install the gems in the instructions
• ensure the .git/hooks dir exists before copying the hook

[tonidero]

Just a note about whether we should force the update to ruby 3.2.0... It might be worth updating in any case so we are in a newer version, but just making sure I understand the issues you found.

[tonidero]

Hmm this might force devs to update their ruby version... Was this needed for some dependency? I've been able to run fine from 3.1.2 with a clean clone, so not sure if it's needed. Were you finding errors in ruby 3.1.2?

[ekurutepe]

The other way around. I had ruby 3.4 installed by default and it was causing compatibility issues with some gems. I think it makes sense to fix the version to the same version as we're using on CI. (which was a mix of 3.2.0 and 3.1.2 before) I think it's ok to encourage devs to use a compatible ruby version since this is only applies to contributors, not for developers using purchase-ios in their apps.

[tonidero]

Ah ok, I was just using 3.1.2 but I don't mind too much to update. Might want to give a heads up in #guild-sdks but looks good!