Update python-app.yml

Author: anki-code

.github/workflows/python-app.yml

@@ -24,7 +24,7 @@ jobs:
       run: |
         echo $(python -V)
         python -m pip install --upgrade pip
-        pip install 'xonsh[full]'
+        pip install -U 'git+https://github.com/xonsh/xonsh'
     - name: Test dev.xonshrc
       run: |
         echo Testing...