Allow opentelemetry-python forks to use CI

Signed-off-by: Josh Soref <[email protected]>

Author: jsoref

.github/workflows/contrib.yml

@@ -10,5 +10,6 @@ jobs:
   contrib_0:
     uses: open-telemetry/opentelemetry-python-contrib/.github/workflows/core_contrib_test_0.yml@main
     with:
+      CORE_REPO: ${{ github.repository }}
       CORE_REPO_SHA: ${{ github.sha }}
       CONTRIB_REPO_SHA: main