[swift5] less restrictive alamofire dependency resolution

[Jonas1893]

Follow up from discussion here: #13667 (comment)
Currently we only allow dependency resolution to resolve Alamofire 5.4.3 and possible future patch versions of 5.4. Since Alamofire is using semver we can safely optimistically resolve to next major version instead without the danger of breaking API changes. Consuming projects can still opt-in whether to use an older version, currently they are forced to use the old 5.4.* versions.

This PR optimistically pins Alamofire to next major version allowing cocoapods / SPM to resolve everything from version 5.4 until and not including version 6.

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[4brunu]

Hey @Jonas1893, thanks for following up with this.
Could you also fix this in Carthage?
What do you think about downgrading the version of Alamofire to something like 5.0 to allow more versions of Alamofire?
Should we also do the same for the other dependencies?

[Jonas1893]

Hey @Jonas1893, thanks for following up with this.
Could you also fix this in Carthage?
What do you think about downgrading the version of Alamofire to something like 5.0 to allow more versions of Alamofire?
Should we also do the same for the other dependencies?

Hi @4brunu sorry forgot about Carthage. Will do 👍

I personally would be against allowing even earlier Alamofire versions as this could unnecessarily introduce a new window of potential bugs. Alamofire 5.4.0 is from November 2020 so I think going with it as minimum version is reasonable, 99.99% of libs and apps with AF dependencies will probably support it now anyway.

Regarding other dependencies: I am not familiar with each and everyone of the dependencies regarding how closely they follow semver. Worst case that can happen for consumers of swift generator if we use the same approach: a new version of a dependency introduces a breaking change in a minor version release, in that case a user of the generator could still pin this dependency to an earlier version in their dependency file as a workaround and it would compile just fine.
We would be aware when regenerating the samples and executing tests where we would have to fix the version constraint again.

So: I think we could try and follow through with this strategy for every third party dependency, if we see that some of the dependencies do not follow semver closely and we would have to fix it often we can revert again. Downside is that if these problems happen then this would have an impact for the whole generator project and swift tests will be failing on CI for every PR even if their changes are unrelated to swift generator

[4brunu]

Looks good to me.

Could you change the other dependencies, except for vapor, since that's a complicated one?
Flight-School/AnyCodable
mxcl/PromiseKit
ReactiveX/RxSwift

Thanks

[4brunu]

Looks good to me 👍