ci(github-workflows): add testing on MacOS and Windows

.github/workflows/plugin-tests.yml

@@ -35,3 +35,27 @@ jobs:
         run: |-
           source venv/bin/activate
           pytest -s
+        shell: bash  # Default shell for macOS and Ubuntu
+
+      - name: Run pytest, compare output with stored snapshots (Linux/macOS)
+        if: runner.os != 'Windows'
+        run: |
+          . venv/bin/activate
+          pytest -s
+        shell: bash
+
+      - name: Install dependencies (Windows)
+        if: runner.os == 'Windows'
+        run: |
+          python -m venv venv
+          venv\Scripts\activate
+          pip install --require-virtualenv --upgrade pip
+          pip install --require-virtualenv '.[test]'
+        shell: cmd
+
+      - name: Run pytest, compare output with stored snapshots (Windows)
+        if: runner.os == 'Windows'
+        run: |
+          venv\Scripts\activate
+          pytest -s
+        shell: cmd