Add Actionlint check for actions

Check the actions in this repo with actionlint and yamllint; make the
filename generic so that other checks can also be added

.github/dependabot.yml

@@ -1,11 +1,12 @@
+---
 # To get started with Dependabot version updates, you'll need to specify which
 # package ecosystems to update and where the package manifests are located.
 # Please see the documentation for all configuration options:
 # https://docs.github.com/github/administering-a-repository/configuration-options-for-dependency-updates
 
 version: 2
 updates:
-  - package-ecosystem: "github-actions" # See documentation for possible values
+  - package-ecosystem: github-actions
     directory: "/" # Location of package manifests
     schedule:
-      interval: "daily"
+      interval: daily

.github/workflows/self_check.yml

@@ -0,0 +1,22 @@
+---
+name: Self Checks
+on: pull_request
+
+jobs:
+  actionlint:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: actionlint
+        uses: raven-actions/actionlint@v2
+  yamllint:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-python@v5
+        with:
+          python-version: '3.13'
+      - name: Install yamllint
+        run: pip3 install yamllint
+      - name: Run yamllint
+        run: yamllint -f github .

.yamllint

@@ -0,0 +1,6 @@
+---
+rules:
+  indentation:
+    spaces: 2
+  line-length:
+    max: 250