Update test.yml with python 3.9.21

Author: jacktasia

.github/workflows/test.yml

@@ -27,7 +27,7 @@ jobs:
       - uses: actions/checkout@v1
       - uses: actions/[email protected]
         with:
-          python-version: '3.7'
+          python-version: '3.9.21'
           architecture: 'x64'
       - uses: purcell/setup-emacs@master
         with: