workflow: add black and isort format checks

.github/workflows/build.yaml

@@ -18,6 +18,7 @@ jobs:
     - uses: actions/checkout@v2
     - name: run
       run: sudo ./scripts/test-in-lxd.sh ${{ matrix.image }} "make check"
+
   lint:
     runs-on: ubuntu-20.04
     strategy:
@@ -31,6 +32,24 @@ jobs:
     - name: lint
       run: sudo ./scripts/test-in-lxd.sh ${{ matrix.image }} "make lint"
 
+  format-black:
+    runs-on: ubuntu-22.04
+    steps:
+      - uses: actions/checkout@v3
+      - uses: psf/black@stable
+        with:
+          version: "~= 23.0"
+          src: "console_conf subiquity subiquitycore system_setup"
+
+  format-isort:
+    runs-on: ubuntu-22.04
+    steps:
+      - uses: actions/checkout@v3
+      - uses: isort/isort-action@v1
+        with:
+          isort-version: "5.12.0"
+          sort-paths: "console_conf subiquity subiquitycore system_setup"
+
   static-typing:
     # In this job, we compare the output of mypy before and after the PR.
     if: github.event_name == 'pull_request'