Add schedule and change Python version for updating dependencies (#3449)

Author: yifanmai

.github/workflows/update-requirements.yml

@@ -11,6 +11,8 @@ on:
     paths:
       - "setup.cfg"
       - '.github/workflows/update-requirements.yml'
+  schedule:
+    - cron: "30 15 * * 1"
   workflow_dispatch:
 
 jobs:
@@ -19,7 +21,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python-version: ["3.10"]
+        python-version: ["3.9"]
     steps:
       - name: Check out repository
         uses: actions/checkout@v4