Add new workflow: yamllint

This should ensure some consistency within the various YAML files.

.github/workflows/linter.yaml

@@ -0,0 +1,28 @@
+---
+name: Run yaml-lint
+on:  # noqa: yaml[truthy]
+  pull_request:
+    branches:
+      - main
+      - stable
+    paths:
+      - "**.yaml"
+      - "**.yml"
+
+jobs:
+  yaml-lint:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Setup python
+        uses: actions/setup-python@v5
+        with:
+          python-version: '3.10'
+
+      - name: Install yaml-lint
+        run: pip install yamllint
+
+      - name: Run yaml-lint
+        run: yamllint -s *