ci: fix ci md2pdf

.github/workflows/upload_COS.yml

@@ -70,8 +70,8 @@ jobs:
     - name: Create PDF
       uses: mkrakowitzer/actions-makepdfs@v1.3
       with:
-        markdown_dir: .\Md
-        output_dir: .\THUAI6\
+        markdown_dir: ./Md
+        output_dir: ./THUAI6/
 
     - name: Tencent Cloud COS Action
       uses: TencentCloud/cos-action@v1