Add black code formatter to continuous integration

.github/workflows/black.yml

@@ -0,0 +1,23 @@
+name: Black code formatter
+
+on:
+  pull_request:
+
+jobs:
+  black:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+
+      - name: Install black
+        run: pip install black
+
+      - name: Get changed python files
+        id: changed-files
+        uses: tj-actions/changed-files@v37
+        with:
+          files: "**/*.py"
+
+      - name: Check changed files
+        if: steps.changed-files.outputs.any_changed == 'true'
+        run: black --check --color --diff --quiet ${{ steps.changed-files.outputs.all_changed_files }}