Increase minimum supported macOS version from 13 Ventura to 15 Sequoia

Increase mas's minimum supported macOS version from 13 Ventura to 15 Sequoia.

This should be done only on the release of a major version.

The known benefits of increasing the minimum macOS version for running mas are (by minimum version):

• 14 Sonoma
  • Observation framework
  • Predicate
  • Sequence.filter(_: Predicate)
  • withDiscardingTaskGroup(…)
  • JSONEncoder.encode(_:configuration:)
  • SortDescriptor
    • .sorted(using: SortDescriptor(\.name, comparator: .localizedStandard)) instead of .sorted { $0.name.localizedStandardCompare($1.name) == .orderedAscending }
• 15 Sequoia
  • Update Swift Subprocess to 1.0.0+
  • Update Swift System to 1.8.0+
  • https://developer.apple.com/documentation/foundation/data/bytes
  • https://github.com/apple/swift-configuration
  • /usr/bin/jq: remove jq brew dependency for 14 Sonoma & earlier
  • /usr/bin/trash
  • ManagedAtomic ➡ Atomic
  • SKPaymentQueue
    • Remove due to deprecation
  • String
    • init(validating:as:)
  • AsyncSequence<Element, Failure> (instead of AsyncSequence<Element>)
    • swift-async-algorithms
  • RangeSet
  • Int128
  • UInt128
• 26 Tahoe
• 27 Golden Gate
  • Drop x86_64 support

Upgrade tasks:

• Remove mas & header code that is no longer needed
  • #available
  • #unavailable
  • @available
  • NS_AVAILABLE_MAC
  • NS_DEPRECATED_MAC
• Replace, e.g.:
  • 12 ➡ 14
  • Monterey ➡ Sonoma
  • 13 ➡ 15
  • Ventura ➡ Sequoia

Mac models that become unsupported by specific macOS versions:

• 14 Sonoma
  • iMac 2017
  • MacBook 2017
  • MacBook Pro 2017
• 15 Sequoia
  • MacBook Air 2018
  • MacBook Air 2019
• 26 Tahoe
  • iMac 21.5" 4K Retina 2019
  • iMac 27" 5K Retina 2019
  • iMac Pro 2017
  • Mac mini 2018
  • MacBook Air 13" Retina 2020
  • MacBook Pro 13" 2018 4 Thunderbolt ports
  • MacBook Pro 13" 2019 2 Thunderbolt ports
  • MacBook Pro 13" 2019 4 Thunderbolt ports
  • MacBook Pro 13" 2020 2 Thunderbolt ports
  • MacBook Pro 15" 2018
  • MacBook Pro 15" 2019
• 27 Golden Gate
  • Mac Pro 2019
  • MacBook Pro 13" 2020 4 Thunderbolt 3 ports
  • MacBook Pro 16" 2019
  • iMac Retina 5K 27" 2020