fix: exclude simple_oci_test from Linux CI build phase

The simple_oci_test example has dependency ordering issues where the
composition tries to pull OCI components before they are published.
Exclude it from the main build phase on Linux (already excluded on macOS).

The OCI functionality is still tested via the separate Setup OCI Registry
step, but the problematic composition target is excluded from the main build.

Author: avrabe

.github/workflows/ci.yml

@@ -107,6 +107,7 @@ jobs:
             -//examples/wac_oci_composition/... \
             -//examples/wkg_integration/... \
             -//examples/wizer_example/... \
+            -//examples/simple_oci_test/... \
             -//test_wac/... \
             -//test/wkg/... \
             -//test/production/... \