now installing dependencies

.github/workflows/unittest_ci.yml

@@ -12,10 +12,18 @@ jobs:
     steps:
     - uses: actions/checkout@v2
 
+    # We could choose to set up dependencies manually in the GHA runner.
+    #
+    # However, I think it's better to do them in the GHA itself so that
+    # we're testing our dependency installation step in addition to our
+    # actual code.
     - name: Set up Python
       uses: actions/setup-python@v4
       with:
         python-version: '3.10'
 
-    - name: Run a script
+    - name: Install dependencies
+      run: ./dependency/install_dependencies.sh
+
+    - name: Run unit tests
       run: python scripts/run_unittests.py