Update dependencies before a build

[bnbarham]

No idea how, but we seem to be fetching repos from caches. Just do an update for now so that we resolve to the latest versions.

[bnbarham]

Still:

Computing version for https://github.com/swiftlang/swift-markdown.git
Computed https://github.com/swiftlang/swift-markdown.git at 0.7.1 (1.25s)
Fetching https://github.com/swiftlang/swift-cmark.git

🤔

[bnbarham]

Okay, so presumably the fetched from cache is a red herring (I assume we download into the cache and then the message is always fetched from cache). So we're actually resolving to 0.7.1 for 6.1 for some reason.

[bnbarham]

I see, that is indeed the case - SwiftPM only resolves to 0.7.1 in <= 6.1 I'm hoping a 0.8 release of swift-markdown will fix this and it's just because we don't check the versioned manifest for patch releases. I'll create a smaller reproducer tomorrow and confirm that. Unfortunately no amount of cleaning will do anything here