Update swift-system dependency to 0.0.2

[finagolfin]

Swift System 0.0.1 is really old and doesn't build on Android.

Information

• Package version: main
• Platform version: Android 11
• Swift version: 5.4

Checklist

• If possible, I've reproduced the issue using the main branch of this package.
• I've searched for existing GitHub issues.

[lorentey]

Swift System 0.0.1 is really old

Swift System 0.0.1 was the most recent public release until yesterday.

[finagolfin]

Oh, just noticed that you updated this dependency for swift-collections last month, so I added that repo to my daily CI for Android, which cross-compiles it with Swift 5.4 and runs its tests in the Android emulator.

[finagolfin]

Closed by #14.