dev/treefmt: add actionlint

.github/workflows/repo-list.yml

@@ -14,7 +14,7 @@ jobs:
       - name: setup
         id: setup
         run: |
-          echo "title=devdoc: update repo list $(date -u +"%Y-%m-%d")" >> $GITHUB_OUTPUT
+          echo "title=devdoc: update repo list $(date -u +"%Y-%m-%d")" >> "$GITHUB_OUTPUT"
           git config user.email "41898282+github-actions[bot]@users.noreply.github.com"
           git config user.name "github-actions[bot]"
       - name: Update repo list

dev/treefmt.nix

@@ -7,6 +7,11 @@
   programs.prettier.enable = true;
 
   settings.formatter = {
+    actionlint = {
+      command = pkgs.actionlint;
+      includes = [ ".github/workflows/*.yml" ];
+    };
+
     nix = {
       command = "sh";
       options = [