Add isort linting to workflows

.github/workflows/lint.yml

@@ -12,3 +12,17 @@ jobs:
         with:
           options: "--check"
           src: "."
+
+  isort:
+    runs-on: ubuntu-latest
+    name: isort linting
+    steps:
+      - uses: actions/checkout@v3
+      - name: Set up Python
+        uses: actions/setup-python@v2
+        with:
+          python-version: '3.x'
+      - name: Install isort
+        run: pip install isort
+      - name: Run isort
+        run: isort --check-only .