ci: extend stylish workflow with flake8 check

In addition to the format with black, check the sources also using
flake8. The job will install flake8 as available in the latest stable
Fedora version.

Use a marketplace action to annotate the files with the result of the
flake8 run.

Signed-off-by: Pino Toscano <ptoscano@redhat.com>

.github/workflows/stylish.yml

@@ -6,7 +6,7 @@ on:
 
 jobs:
   stylish:
-    name: "black"
+    name: "black & flake8"
     runs-on: ubuntu-latest
     container:
       image: fedora:latest
@@ -16,10 +16,18 @@ jobs:
       run: |
         dnf --setopt install_weak_deps=False install -y \
             git-core \
+            python3-flake8 \
             python3-pip
 
     - uses: actions/checkout@v4
 
     - uses: psf/black@stable
       with:
         version: "24.2.0"
+
+    - name: Setup flake8 annotations
+      uses: rbialon/flake8-annotations@v1
+
+    - name: Run flake8
+      run: |
+        flake8