message: Add gltf-validator to gltfpack CI
  We now convert all .gltf models using gltfpack and run them through
  gltf-validator to make sure the output is valid.
diff: @@ -77,3 +77,11 @@ jobs:
  run: make -j2 config=debug gltfpack
  - name: test
  run: find glTF-Sample-Models/2.0/ -name *.gltf | xargs ./gltfpack -cc -test
  + - name: pack
  + run: find glTF-Sample-Models/2.0/ -name *.gltf | xargs -I '{}' ./gltfpack -i '{}' -o '{}-pack.gltf'
  + - name: validate
  + run: |
  + curl -sL $VALIDATOR | tar xJ
  + find glTF-Sample-Models/2.0/ -name *-pack.gltf | xargs -L 1 ./gltf_validator -r -a
  + env:
  + VALIDATOR: https://github.com/KhronosGroup/glTF-Validator/releases/download/2.0.0-dev.3.2/gltf_validator-2.0.0-dev.3.2-linux64.tar.xz
  