Fix CI (#3296)

Author: hekaisheng

.github/workflows/os-compat-ci.yml

@@ -18,7 +18,7 @@ jobs:
  fail-fast: false
  matrix:
  os: [macOS-latest, windows-latest]
- python-version: [3.7, 3.8]
+ python-version: [3.9]
 
  steps:
  - name: Check out code

.github/workflows/platform-ci.yml

@@ -88,7 +88,7 @@ jobs:
  ./ci/install-hadoop.sh
  echo "import coverage; coverage.process_startup()" > \
  $(python -c "import site; print(site.getsitepackages()[-1])")/coverage.pth
- conda install -n test --quiet --yes -c conda-forge python=$PYTHON skein conda-pack
+ conda install -n test --quiet --yes -c conda-forge python=$PYTHON skein libffi conda-pack
  fi
  if [ -n "$WITH_VINEYARD" ]; then
  pip install vineyard -i https://pypi.org/simple

azure-pipelines.yml

@@ -77,7 +77,7 @@ jobs:
  conda install -n test --quiet --yes -c pkgs/main python=$PYTHON certifi
 
  if [[ "$(mars.test.module)" == "learn" ]]; then
- pip install "xgboost<1.7" lightgbm keras tensorflow faiss-cpu torch torchvision \
+ pip install "xgboost<1.7" lightgbm keras tensorflow faiss-cpu\<1.7.3 torch torchvision \
  statsmodels tsfresh
  fi
  fi