feat(CI): Add HACS validation step to Github Actions

.github/workflows/python-app.yml

@@ -50,3 +50,12 @@ jobs:
     - name: Test with pytest
       run: |
         poetry run pytest
+
+  validate:
+    runs-on: "ubuntu-latest"
+    steps:
+      - uses: "actions/checkout@v2"
+      - name: HACS validation
+        uses: "hacs/action@main"
+        with:
+          category: "integration"