Support the special version "MIN"

[omus]

Introduces a special version "MIN" which when passed in as the version allows the user to test against the earliest version of Julia compatible with their project. In order to determine this version the project file is read.

If we want we can choose another name for this special version but I would like to keep the name short as this usually appears in the CI check name which can already be quite long.

[omus]

Did some basic local testing but need to add real tests before this is ready for review

[DilumAluthge]

Does this work for all julia = "..." compat entries, or just some? Can we document which ones it works for?

[DilumAluthge]

Can you add tests for:

1. Multiple entries separated by comma, e.g. ~1.7, ~1.8, ~1.9
2. Hyphen ranges, e.g. 1.7 - 1.9

[DilumAluthge]

And probably should also add tests for inequalities:

1. < 1.9.0
2. >= 1.6.0

[DilumAluthge]

Probably also want to test the "multiple comma-separated entries" with a couple different permutations.

So e.g. we should test julia = "~1.7, ~1.8, ~1.9.

But we should also test julia = "~1.8, ~1.7, ~1.9 and make sure it gives the same result.

[omus]

I'll add tests for all of these but based upon what I've seen in https://github.com/npm/node-semver#ranges all of these should work

[omus]

Done