Fix testing on Windows with GH Actions

Author: grossmj

.github/workflows/testing.yml

@@ -20,8 +20,15 @@ jobs:
         os: [ubuntu-latest, windows-latest]
         python-version: ["3.8", "3.9", "3.10", "3.11", "3.12"]
         exclude:
-          - os: windows-latest # only test with Python 3.10 on Windows
-            python-version: ["3.8", "3.9", "3.11", "3.12"]
+          # only test with Python 3.10 on Windows
+          - os: windows-latest
+            python-version: "3.8"
+          - os: windows-latest
+            python-version: "3.9"
+          - os: windows-latest
+            python-version: "3.11"
+          - os: windows-latest
+            python-version: "3.12"
 
     steps:
     - uses: actions/checkout@v4
@@ -32,7 +39,7 @@ jobs:
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip
-        if [ -f dev-requirements.txt ]; then pip install -r dev-requirements.txt; fi
+        python -m pip install -r dev-requirements.txt
     - name: Lint with flake8
       run: |
         # stop the build if there are Python syntax errors or undefined names