update setup and workflow (#222)

.github/workflows/PR_CI.yml

@@ -43,7 +43,7 @@ jobs:
       - name: Install Colossal-AI      
         run: |
           pip install -r requirements/requirements.txt
-          pip install -v --no-cache-dir --global-option="--cuda_ext" .
+          pip install -v --no-cache-dir .
       - name: Unit Testing
         run: |
           pytest tests