[Swift 6]: Update Exercises batch 17

[meatball133]

Includes:

• Space-age
• Strain
• Sublist
• Sum-of-multiples

Noteworthy changes:

Addition of the swift library: https://github.com/apple/swift-numerics, this is due to that the new testing library has no proper way of comparing floating point numbers,

The testing library doesn’t provide an equivalent of XCTAssertEqual(::accuracy:_:file:line:). To compare two numeric values within a specified accuracy, use isApproximatelyEqual() from swift-numerics.

[github-actions]

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