Re-enable the tests that get skipped on GitHub CI

[bramus]

The navigation tests that rely on pagereveal and pageswap consistently fail when ran in the GitHub CI. Changing the OS from ubuntu-latest to macos-latest seems to have no effect.

These tests are now manually skipped when GitHub CI is detected: https://github.com/GoogleChromeLabs/view-transitions-toolkit/blob/main/tests/navigation.pw.test.ts#L13-L14

    // Skip test when run inside a GitHub action
    test.skip(!!process.env.GITHUB_RUN_ID, "Failing in GitHub Actions");

Ideally these should be re-enabled but it’s not 100% urgent as tests also run locally before code gets pushed.