update collection-index.yml - remove collection for Airplane.dev CLI (devcontainers#530)

Author: RouL

_data/collection-index.yml

@@ -338,11 +338,6 @@
   contact: https://github.com/ksh5022/devcontainer-features/issues
   repository: https://github.com/ksh5022/devcontainer-features
   ociReference: ghcr.io/ksh5022/devcontainer-features
-- name: GMkonan devcontainer features
-  maintainer: GMkonan
-  contact: https://github.com/GMkonan/feature/issues
-  repository: https://github.com/GMkonan/feature
-  ociReference: ghcr.io/gmkonan/feature
 - name: Dapr devcontainer features
   maintainer: Dapr maintainers
   contact: https://github.com/dapr/cli/issues