Fix excludes ant pattern on Windows

[trask]

Fixes this use case on Windows:

  relocate('io.opentelemetry', 'io.opentelemetry.auto.shaded.io.opentelemetry') {
    exclude 'io.opentelemetry.auto.**'
  }

The fix is to explicitly pass separator (/) to SelectorUtils.matchPath. The default when it's not passed is File.separator, so this change should have no effect on non-Windows OS.

[trask]

Thx!