Update python-app.yml

change pip source from  http://mirrors.aliyun.com/pypi/simple/ to  https://mirrors.aliyun.com/pypi/simple/

.github/workflows/python-app.yml

@@ -26,7 +26,7 @@ jobs:
         python-version: "3.9"
     - name: Install dependencies
       run: |
-        python -m pip config set global.index-url http://mirrors.aliyun.com/pypi/simple/
+        python -m pip config set global.index-url https://mirrors.aliyun.com/pypi/simple/
         python -m pip install --upgrade pip
         python -m pip install flake8 pytest
         python -m pip install torch