Exclude Info plists from SwiftPM target

[fwcd]

When building the project from the command-line using swift build, SwiftPM currently warns about not excluding a couple of plists:

$ swift build
warning: 'swiftsoup': found 4 file(s) which are unhandled; explicitly declare them as resources or exclude from the target
    <path to swiftsoup>/Sources/InfoMac.plist
    <path to swiftsoup>/Sources/InfotvOS.plist
    <path to swiftsoup>/Sources/Info.plist
    <path to swiftsoup>/Sources/InfoWatchOS.plist
Building for debugging...
[63/63] Compiling SwiftSoup resource_bundle_accessor.swift
Build complete! (5.22s)

This PR fixes the issue by adding the missing excludes (I assume the plists are used by some other build mechanism).