Update publish_to_test_pypi.yml

Author: lckr

.github/workflows/publish_to_test_pypi.yml

@@ -20,7 +20,7 @@ jobs:
         python-version: '3.7'
         architecture: 'x64'
     - name: Install dependencies
-      run: python -m pip install jupyterlab
+      run: python -m pip install jupyterlab jupyter_packaging
     - name: Build
       run: |
         jlpm