Unpin ninja version (#2358)

Author: peterjc123

packaging/build_wheel.sh

@@ -7,7 +7,7 @@ script_dir="$( cd "$( dirname "${BASH_SOURCE[0]}" )" >/dev/null 2>&1 && pwd )"
 export BUILD_TYPE=wheel
 setup_env 0.8.0
 setup_wheel_python
-pip_install numpy pyyaml future "ninja==1.9.0.post1"
+pip_install numpy pyyaml future ninja
 setup_pip_pytorch_version
 python setup.py clean
 if [[ "$OSTYPE" == "msys" ]]; then