ci: remove zenfaces/zentract clones (private repos, not needed)

zenfaces/zentract don't have public GitHub repos. They're only reached
via zenpipe's nodes-faces feature which uses dep: syntax (2021 edition
weak optional deps) — since nodes-faces is never enabled in our feature
set, Cargo won't try to resolve those paths.

Author: lilith

.github/workflows/ci.yml

@@ -175,9 +175,6 @@ jobs:
           # Unified codec/pipeline dispatch
           git clone --depth 1 https://github.com/imazen/zencodecs.git       ../zen/zencodecs
           git clone --depth 1 https://github.com/imazen/zenpipe.git         ../zen/zenpipe
-          # AI/face features (optional path deps still need to exist)
-          git clone --depth 1 https://github.com/imazen/zenfaces.git        ../zen/zenfaces
-          git clone --depth 1 https://github.com/imazen/zentract.git        ../zen/zentract
           # Metrics/testing
           git clone --depth 1 https://github.com/imazen/zensim.git          ../zen/zensim