fix typo in CI

.github/workflows/unit_test.yml

@@ -26,7 +26,7 @@ jobs:
       run: |
         python -m pip install --upgrade pip
         if [ -f requirements.txt ]; then pip install -r requirements.txt; fi
-        if [ -f requirements-dev.txt ]; then pip install -r requirements-test.txt; fi
+        if [ -f requirements-dev.txt ]; then pip install -r requirements-dev.txt; fi
     - name: Lint with flake8
       run: |
         # stop the build if there are Python syntax errors or undefined names