Update python-app.yml

Add PostgreSQL to PATH
https://docs.github.com/en/actions/writing-workflows/choosing-what-your-workflow-does/workflow-commands-for-github-actions#setting-an-environment-variable

.github/workflows/python-app.yml

@@ -85,13 +85,17 @@ jobs:
         python -m pip install --upgrade pip
         pip install wheel
 
+    - name: Add PostgreSQL to PATH
+      run: |
+        echo "$PGBIN" >> "$GITHUB_PATH"
+
     - name: Setup Graphviz
       uses: ts-graphviz/setup-graphviz@v2
       with:
         macos-skip-brew-update: 'true' # default false
         windows-graphviz-version: '2.49.3'
 
-    - name: register plugins for graphviz
+    - name: Register plugins for Graphviz
       if: ${{ runner.os == 'Windows' }}
       run: |
         dot -V