Update python-app.yml

Author: notactuallyfinn

.github/workflows/python-app.yml

@@ -24,8 +24,7 @@ jobs:
       run: |
         python -m pip install --upgrade pip
         pip install pytest
-        pip install .
-        pip install .[dev]
+        pip install -e .[dev]
     - name: Test with pytest
       run: |
         pytest --cov=src test/hermes_toml_test