Add fallback if swiftlint fails

[dostrander]

• Currently swiftlint fails if you are on a old version of it. There should be a fallback when it fails and some type of recommended next step.

[codecov-io]

Current coverage is 85.67% (diff: 100%)

Merging #865 into master will not change coverage

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[jpsim]

This isn't quite right. For one, swiftlint || echo "..." will always have a return code of 0.

Even if that were addressed, always logging "Is SwiftLint installed and up to date?" no matter of the reason of the failure is misleading.

Seems like overall, this PR aims to address a larger issue, which is one of version enforcement and compatibility, for which discussions around potential strategies to resolve are actively happening in #221. I'd prefer focusing our energies on finding a good solution.